KR102142273B1 - Displayport and data transmitting method of displayport - Google Patents

Abstract

According to an embodiment of the present invention, in order to solve the above problems, it is possible to repeatedly perform link training until the link training is successful by using the HPD signal forming the repeated toggle signal, and to stop the link training. It is possible to provide a display port and a display port data transmission method separately provided with a link training request unit for controlling, and also when a transmitter and a receiver are connected, generate a periodic HPD signal, and when the HPD signal is initially broken Also, link training may be performed between the transmitter and the receiver using an additionally generated HPD signal, and the link training is always performed regardless of the type of the transmitter applied to the receiver by varying the interval when the toggle of the HPD signal is generated. It is also an object to provide a highly compatible DisplayPort and a method for transmitting data of the DisplayPort by making the request again.

Description

DisplayPort and Data Transmission Method of DisplayPort{DISPLAYPORT AND DATA TRANSMITTING METHOD OF DISPLAYPORT}

The present invention relates to a display port and a data transmission method of the display port.

Due to characteristics such as light weight, thinness, and low power consumption, the display device is gradually expanding its application range.

The display device is used as a portable computer such as a notebook PC, office automation equipment, video/video equipment, and indoor and outdoor advertising display devices.

Among the display devices, the liquid crystal display device controls the electric field applied to the liquid crystal cells to modulate light incident from the backlight unit to display an image.

Meanwhile, with the development of image technology, a high-resolution display interface has been developed. Currently, a variety of next-generation display technologies such as UHD and 3D displays are appearing.

In order to satisfy a user's demand for high-quality display performance, a liquid crystal display device is in a trend of realizing high-quality images with a high video data channel transmission bandwidth and a high frame refresh rate.

LVDS, VGA, DVI, and HDMI interface methods are mainly used in current displays.

In a current TV set system, a system on chip (hereinafter referred to as "SoC") that generates video data to be displayed on a display panel, and a control circuit operating timing of a display panel Video data transmission between timing controllers uses a Low Voltage Differential Signaling (LVDS) interface.

The LVDS interface has the advantage that it is less affected by low power consumption and external noise by using a low voltage swing level and a differential signal pair, but it has a high resolution due to the limitation of its data transmission speed. ) Is unsuitable for video data transmission.

The Display Port (DP) interface is an interface established by the Video Electronics Standards Committee (VESA). It integrates the existing internal interface standard LVDS and the external connection standard Digital Visual Interface (DVI) to connect to one. Interface method.

DisplayPort interface is a technology that can digitally connect not only the internal connection between the chip and the chip, but also the external connection between the product and the product.

By combining the two divided interfaces into one, the data bandwidth can be widened to support higher color depth and resolution.

The display port interface has a bandwidth of up to 10.8 Gbps, which is more than twice that of the existing DVI (up to 4.95 Gbps), and supports multiple streams with a micro-packet architecture, allowing up to 6 1080i streams (3 1080p) with one connector ) At the same time.

In addition, it is equipped with a bi-directional auxiliary channel with a 1 Mbps bandwidth, and can support applications such as video chat and Internet phone (VoIP) without a separate interface.

The display port may be composed of a transmitter that transmits data, a receiver that receives the transmitted data, and links connecting them. In addition, it is possible to recognize that the transmitter and the receiver are connected by using a hot plug detect (HPD) signal.

When the transmitter and the receiver are first connected, the transmitter may receive an HPD signal from the receiver and perform a link training process to optimize the links to transmit a stream.

When the link training process is completed, stream data may be transmitted from the transmitter to the receiver.

In this case, DisplayPort needs CDR (Clock Data Recovery) between transmitter and receiver due to the communication characteristics. However, if the communication timing between the transmitter and receiver of the CDR is not correct, the normal display is not possible.

In addition, when the link training process fails during the initial connection between the transmitter and the receiver, there is a problem that data transmission cannot be performed.

That is, when power on, the transmitter (Source) does not display normally even when the initial constant time is incorrect.

In addition, in an abnormal environment such as ESD, the HPD signal is broken and it may not be possible to restore the normal display.

In addition, even if the initial link training process was successful, synchronization between the transmitter and the receiver was broken due to an external factor such as static electricity, and it was necessary to perform the link training process again. A phenomenon in which the aforementioned problem cannot be solved occurred in that the link training process was performed.

In order to solve the above problems, an embodiment according to the present invention is repeated until the link training is successful by using the HPD signal forming the repeated toggle signal, and data transmission of the display port and the display port to perform the link training The purpose is to provide a method.

In addition, it is an object of the present invention to provide a display port and a method for transmitting data of a display port separately equipped with a link training request unit for controlling to stop link training.

In addition, when a transmitter and a receiver are connected, a display port and a display that generate a periodic HPD signal and perform link training between the transmitter and the receiver using an additionally generated HPD signal even when the HPD signal is initially broken The purpose is to provide a method for transmitting data on a port.

Also, it is an object of the present invention to provide a highly compatible display port and a method for transmitting data of the display port by allowing the link training to be re-requested regardless of the type of transmitter applied to the receiver by different sections when generating the toggle of the HPD signal. .

A display port data transmission method according to an embodiment of the present invention is a data transmission method of a display port composed of a transmitter and a receiver, and a link composed of a main link, an auxiliary channel, and a hot plug detect (HPD), stream data from the transmitter to the receiver And a link service step of performing a link training process for optimizing the state of the link by using the device service step of determining whether to transmit or not and the signal of the HPD generating a repeated toggle signal, and the link training The step includes forming a link clock lock and a symbol lock, and the toggle signal is not generated when the link training is successful.

DisplayPort data transmission method according to an embodiment of the present invention further comprises the step of recognizing the initial connection of the transmitter and the receiver using the HPD signal.

In accordance with an embodiment of the present invention, a method for transmitting display port data includes the transmitter comprising a transmitter link policy maker, a transmitter stream policy maker and a transmitter stream source, and the receiver is a receiver link policy maker, a receiver stream policy maker and a receiver stream source, The step of recognizing the connection between the transmitter and the receiver using the HPD signal, including DisplayPort Configuration Data (DPCD) and EDID (Extended Display Identification Data), the transmitter link policy maker receives the HPD signal and the transmitter stream policy maker And informing that a sink device is connected to the device service step, wherein the transmitter stream policy maker reads information about the display device from the receiver stream policy maker and the EDID through a read operation of the EDID, and the main stream. Comparing the attribute data and information of the info-frame data generator, the link service step, the transmitter link policy maker reads the data of the DPCD to start link training and the transmitter to the receiver in advance And restoring a clock by transmitting a predetermined pattern.

In the method of transmitting display port data according to an embodiment of the present invention, the receiver further includes the link training request unit, and the link training request unit reads link training success information from the DPCD and does not output a toggle signal from the HPD. To prevent the data transmission method of the display port to apply a control signal to the HPD.

In the display port data transmission method according to an embodiment of the present invention, when the link training is successful, storing the result of the successful link training in the DPCD, the transmitter link policy maker reads the link training success result from the DPCD And the transmitter link policy maker requesting the receiver link policy maker so that the HPD does not generate a toggle signal.

In the display port data transmission method according to an embodiment of the present invention, when the link training is successful, storing the success result of the link training in the DPCD, the receiver link policy maker reads the link training success result from the DPCD And the receiver link policy maker requesting the HPD so that the HPD does not generate a toggle signal.

In the method of transmitting display port data according to an embodiment of the present invention, the HPD signal is a toggle signal having a low logic.

In the display port data transmission method according to an embodiment of the present invention, when the link training is successful, the HPD signal is a signal for maintaining a high signal.

DisplayPort data transmission method according to an embodiment of the present invention is a data transmission method of the DisplayPort, which is a toggle generation cycle signal of the HPD signal.

In a method of transmitting display port data according to an embodiment of the present invention, a toggle generation period of the HPD signal is longer than a time taken to perform the link training.

In the method of transmitting display port data according to an embodiment of the present invention, the time interval between adjacent toggle signals increases as the HPD signal goes from the first to the Nth (N is an integer) th toggle signal.

A method of transmitting display port data according to an embodiment of the present invention, wherein the link service step includes a main link service step and an auxiliary channel link service step.

A method of transmitting display port data according to an embodiment of the present invention is a method of transmitting data of a display port, wherein the transmitter and the receiver perform isochronous transmission.

The display port according to an embodiment of the present invention includes a transmitter and a receiver, and a link connecting the transmitter and the receiver, wherein the link is composed of a main link, an auxiliary channel, and a Hot Plug Detect (HPD), and the transmitter and the receiver The link training to form a link clock fixed and symbol fixed to each other is performed by a toggle signal generated from the HPD, and the HPD forms a repeated toggle signal.

In the display port according to an embodiment of the present invention, the toggle generation period of the HPD signal is longer than the time taken to perform the link training.

In the display port according to an embodiment of the present invention, the HPD signal is a first to Nth (N is an integer) th toggle signal.

Display port according to an embodiment of the present invention, the transmitter includes a transmitter link policy maker that manages the link, and the receiver is a DisplayPort Configuration Data (DPCD) that stores information regarding the state of the link and the receiver link policy maker. Including, the transmitter link policy maker reads the success result of the link training from the DPCD (Read) the display port to request the receiver link policy maker so that the HPD signal does not form a toggle signal.

The display port according to an embodiment of the present invention, the receiver includes a receiver link policy maker and a display port configuration data (DPCD) storing information on the state of the link, and the receiver link policy maker results in success of the link training Display port for controlling the HPD so that the HPD signal does not form a toggle signal by reading from the DPCD.

The display port according to an embodiment of the present invention, the receiver includes a DisplayPort Configuration Data (DPCD) and a link training request unit storing information on the state of the link, and the link training request unit is configured to display the success result of the link training. A display port that reads from a DPCD to control the HPD so that the HPD signal does not form a toggle signal.

The display port according to an embodiment of the present invention includes a display port configuration data (DPCD) and a link training request unit storing information on the state of the link, and the link training request unit fixes a link clock between the transmitter and the receiver. Alternatively, a display port for controlling the HPD so that the HPD signal forms a toggle signal by reading a result of the symbol fixation broken from the DPCD.

According to an embodiment of the present invention, the link training is repeatedly performed until the link training is successful using the HPD signal generating the repeated toggle signal.

In addition, when the transmitter and the receiver are connected, a periodic HPD signal is generated, so that even if the HPD signal is initially broken, link training is performed between the transmitter and the receiver using the additionally generated HPD signal.

Furthermore, there is an effect of providing a highly compatible display port and a data transmission method of the display port by allowing the link training to be re-requested at all times, regardless of the type of the transmitter applied to the receiver by different sections when generating the toggle of the HPD signal. .

1 is a view showing a display port according to an embodiment of the present invention.
2 and 3 are views showing the structure of the display port.
4 is a view showing the HPDS and link training timing.
5 to 7 are views showing a display port.
8 is a view showing the signal of the HPDS.
9 is a diagram showing link training timing between HPDS and a plurality of transmitters and a single number of receivers.

Hereinafter, a description will be given in detail with reference to drawings of a display port and a data transmission method of the display port according to an embodiment of the present invention. The embodiments introduced below are provided as examples in order to sufficiently convey the spirit of the present invention to those skilled in the art. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. In addition, in the drawings, the size and thickness of the device may be exaggerated for convenience. Throughout the specification, the same reference numbers indicate the same components.

<Terms for explaining DisplayPort according to an embodiment of the present invention>

In describing the display port according to an embodiment of the present invention, terms appearing are first summarized.

The DisplayPort transmitter can transmit data of the DisplayPort main link and the auxiliary channel.

The display port receiver may receive data of a display port main link and an auxiliary channel.

Isochronous transmitter (Isochronous transmitter) is one of the data transmission method, refers to the transmission of video or audio information as the original data flow. Isochronous data transmission enables a display device to receive video and audio data and reproduce it at a constant speed on the screen.

The link layer may be composed of blocks for providing isochronous transmission service (isochronous transmission, micro packet) and link and device service (DPCD (DisplayPort Configuration Data), EDID (Extended Display Identification Data)).

The link policy maker is a block used to manage and maintain the main link, and may have both a source device as a transmitter and a sink device as a receiver.

The physical layer may consist of a logical sub-block (data scrambling/unscrambling, ANSI8B/10B, Manchester II)) and an electrical sub-block (SERDES, differential current actuation/reception).

Manchester transmission mode refers to a transmission mode using a Manchester encoding method used for data transmission of 1 Mbps through an auxiliary channel.

The main link is a unidirectional high-speed channel for isochronous stream transmission as a main transmission channel of stream data, and may be used in 1,2 or 4 lanes, and may be composed of differential pairs. And it can have bit rates of 5.4 Gpbs, 2.7 Gbps, and 1.62 Gbps per lane.

The main stream attributes are attribute data values expressed in the main video stream format or color format, inserted into a video blanking section, and transmitted, and can be used when the receiver reconstructs the stream.

The auxiliary channel (Auxiliary Channel) is a half-duplex bidirectional channel and may be configured as a pair of differential pairs. And it has a bandwidth of 1 Mbps using Manchester coding and a bandwidth of 720 Mbps in a high-speed auxiliary channel format.

The start of the transaction of the secondary channel starts at the transmitter corresponding to the upper device, and the receiver can respond to the transmitter corresponding to the lower device.

The auxiliary channel can be used to initiate and configure the link.

A source device may be a device that starts data on a display port, and may correspond to the root of a display port tree topology.

The sink device may correspond to a device that receives data from the display port and a leaf of the display port tree topology.

Stream Policy Maker is a block used to manage isochronous stream transmission.

Info-Frame data contains information such as audio channel, coding type, and sampling frequency, and can be defined in the CEA-861 profile.

Hot plug detection (HPD) is a signal line for informing a transmitter of a receiver connection, and a signal generated by HPD may be referred to as a Hot Plug Dectect Signal (HPDS).

DPCD (DisplayPort Configuration Data) is a memory located in the sink device and contains the performance of the receiver and the status information of the DisplayPort link.

EDID (Extended Display Identification Data) refers to the memory that contains the display device manufacturer, date of manufacture, serial number, and supported resolution.

The link training request unit may request that link training be performed again when link training fails.

The high-speed transmission mode may be a transmission mode using an 8B/10B encoding method used for data transmission of 720 Mbps through an auxiliary channel.

<Explanation on the link of the display port>

1 is a view showing a display port according to an embodiment of the present invention.

Referring to Figure 1, looks at the link of the display port 10 according to an embodiment of the present invention.

DisplayPort's link consists of Main Link, Aux CH, and Hot Plug Detect (HPD).

The main link is a unidirectional channel, which is a channel having a high bandwidth and a short call time, and can be used for isochronous stream transmission such as uncompressed video data and audio.

The auxiliary channel is a semi-duplex bidirectional channel and can be used for link management and device control.

In addition, the auxiliary channel can be used as a high-speed bidirectional bus capable of transmitting data of other devices at high speed after managing the link and controlling the device.

The HPD signal line may be used as a connection and blocking signal by a sink device, and may output a Hot Plug Detect Signal (HPDS) from the receiver 200 to the transmitter 100.

Hereinafter, the main link and the auxiliary channel of the display port 10 according to an embodiment of the present invention will be described in detail.

<Explanation of main link>

The main link may consist of a dual terminal differential pair of AC connections.

Through AC connection, the transmitter 100 and the receiver 200 may have different common mode voltages.

For example, based on the DisplayPort 1.2 standard, the main link is composed of a total of 4 lanes, and one lane is a bandwidth of 5.4 Gbps, 2.7 Gbps, and 1.62 Gbps. It can be used selectively depending on the condition.

The number of lanes of the main link selectively uses 1, 2, or 4 lanes according to the capacity of the video data, thereby enabling low power saving data transmission.

If 4 lanes are used with a bandwidth of 5.4 Gbps, a bandwidth of 21.6 Gbps can be used.

As an example, a unique channel for clock transmission may not be required by extracting from the data stream itself encrypted using the ANSI 8B/10B coding rule.

<Description of auxiliary channel>

The auxiliary channel is a half-duplex (bidirectional) channel and may be configured as a dual differential pair of AC connections.

It is used for main link management and device control, and after device management control, it enables high-bandwidth data transmission such as USB, CAM (Camera Module), and control data through an auxiliary channel.

As an example, Manchester II coding and ANSI 8B/10B coding can be used, and are used for low-speed and high-speed data transmission, respectively.

Like the main link, the clock CLK is extracted from the data stream, and the source device 100, which is a transmitter for generating video data, corresponds to the master, and the sink device 200 that receives the data is transmitted to the slave. Correspondingly, all auxiliary channel transactions can be initiated at the source device, which is the transmitter.

<Explanation of the structure of the display port>

2 is a view showing the structure of the display port.

Referring to Figure 2, the structure of the display port 10 according to an embodiment of the present invention, the display port 10 is largely composed of a link layer (link layer) and a physical layer (Physic Layer; PHY Layer) Can be.

The link layer may provide isochronous transmission service, auxiliary channel (AUX CH) device service, and auxiliary channel link service.

The physical layer may be composed of an HPD signal transmission unit, an auxiliary channel unit, and a main link unit, and again composed of logical sub-blocks and electrical sub-blocks.

The logical sub-block is a block capable of data scrambling and encryption (ANSI 8B/10B, Manchester encoding), and the electrical sub-block may belong to a serializer, a differential current actuator, or an equalizer.

In addition, the source device that is the transmitter 100 may include a transmitter link policy maker 110, a transmitter stream policy maker 120, and a transmitter stream source 130, and the sink device, which is the receiver 200, is a receiver link policy maker ( 210), a receiver stream policy maker 220 and a receiver stream source 230, the receiver 200 may further include a DPCD (300) and EDID (400).

The stream policy makers 110 and 210 are blocks that manage data streams of the main link, and may function to initialize the main link data stream and manage devices, and link information from the link policy makers 120 and 220. It can play a role of reading.

The link policy makers 120 and 220 are blocks for managing the main link, and may serve to manage the link while discovering, initializing, and maintaining the link.

The link policy makers 120 and 220 may be controlled by firmware, hardware, software, or a state machine.

The DPCD 300 may store information on the state of the link.

The HPD can periodically generate a toggle signal from high to low. Since the toggle signal is not generated when the link training is normally operated, the signal output from the HPD can maintain a high signal.

The transmitter link policy maker 110 may read the link training result from the DPCD 300.

If the link training is successful in the DPCD 300, the result is stored. Therefore, the transmitter link policy maker 110 may read the link training result from the DPCD 300, and the transmitter link policy maker 110 may request the receiver link policy maker 210 to control the HPD, and the receiver The link policy maker 210 may control the HPD to maintain a high signal, that is, a toggle signal is no longer formed.

Thus, no further link training is performed, and stream transmission from the transmitter 100 to the receiver 200 is possible.

In another method, the receiver 200 may further include a link training request unit 500 separately.

The DPCD 300 stores the link training result and provides this information to the link training request unit 500 when the link training is successful, so that the link training request unit 500 may not request the HPD to generate a toggle signal. have.

In addition, the link training request unit 500 reads information on the state of the link from the DPCD 300, and the link clock and the symbol fixation between the current transmitter 100 and the receiver 200 fail. If it is determined, it can be controlled to output a toggle signal, HPDS (Hot Plug Detec Signal) from HPD. Accordingly, since link training may be performed, the HPDS may be a signal requesting that link training be performed.

<Description of the data transmission method of the display port>

The data transmission method of the display port 10 according to an embodiment of the present invention largely performs the following operations.

First, recognizing the connection between the transmitter and the receiver

Second, the device service stage

Third, the main link service stage

Fourth, auxiliary channel link service stage

Through the above process, data transmission between the transmitter 100 and the receiver 200 may be performed.

In particular, if the main link service step or the auxiliary channel link service step is not normally performed, a step of repeating each step may be added, in which case the link training request unit 500 and the HPD and DPCD 300 send information to each other. By transmitting, link training can be performed again.

Each step described above will be described in detail.

First, the step of recognizing the connection between the transmitter 100 and the receiver 200 will be described in detail.

The step in which the transmitter 100 recognizes the connection of the receiver 200 is a step in which a display device is connected to the transmitter link policy maker 110, and the transmitter link policy maker 110 receives the HPD signal (HPDS) and transmits the transmitter stream. It informs that the receiver 200 which is a sink device is connected to the policy maker 120.

In addition, the HPDS is a link training request toggle signal. When information on which link training is not normally performed is read from the DPCD 300, the HPD signal HPDS is generated again so that the link training is repeatedly performed. can do.

Specifically, the HPDS maintains a logical signal of 1 while the display device is operating, and may be a toggle signal that is a logical signal of 0 when link training is requested.

Through the technique of performing link training again using HPDS that can be repeatedly output, link training, which will be described later, is finally successful, so that normal data transmission is possible.

Second, the steps of performing the device service will be described in detail.

The step of performing device service is performed by the transmitter stream policy maker 120 from the receiver stream policy maker 220 and the receiver 200 EDID 400 through the read operation of the EDID 400 of the receiver 200. Read information about. In addition, it is possible to determine whether to transmit stream data comparing the EDID 400 information read by the transmitter stream policy maker 120 with information of the main stream attribute data and the info-frame data generator.

This is a step of initializing the stream transmission. The transmitter stream policy maker 120 reads display related information from the EDID 400 of the receiver 200 to initialize the stream transmission to be transmitted through the main link, and the main stream properties The stream properties to be transmitted are set by using the data and the info-frame generator, and information such as a bandwidth of a link and a receivable port of the receiver 200 can be obtained from the receiver link policy maker 210.

Third, in the step of performing the main link service, the transmitter link policy maker 110 operates after the device service described above, and the transmitter link policy maker 110 reads the data of the DPCD 300 of the receiver 200 and performs link training. Can start.

Through the link training, a main link service that optimizes the state of the main link may be performed.

When the device service step and the main link service step are performed as described above, preparation for transmitting a stream from the transmitter 100 to the receiver 200 may be completed.

When the stream is ready for transmission, the transmitter stream policy maker 120 starts isochronous transmission of the stream with the stream attribute data.

The receiver 200 interprets the received stream attribute data and reconstructs the isochronous stream only when receiving stable data.

The receiver stream policy maker 220 may integrate link performance information for stream source management.

When the stream exceeds the link bandwidth, the receiver stream policy maker 220 may transmit an error correction signal to the stream source by lowering the resolution or color depth of the transmitted image.

Hereinafter, a method of optimizing the state of the main link in the step of performing the main link service will be described.

In order to transmit an isochronous data stream from the transmitter 100 to the receiver 200 through the main link of the display port 10, a link must be formed through a process called a link service.

In order to configure the main link, the transmitter link policy maker 110 receives link performance information of the DPCD 300 containing performance information of the receiver 200, such as the maximum bandwidth of the receiver 200 and the maximum number of lanes used through the auxiliary channel. Read to initialize the link configuration.

Link training is started by transmitting a training pattern through the main link, and the receiver link policy maker 210 stores the training status and results in the DPCD 300, so that the transmitter link policy maker 110 is DPCD Through the reading process of 300, the result of link training can be checked through the auxiliary channel.

If the link training is unsuccessful, the receiver link policy maker 220 performs differential voltage width correction and pre-emphasis reset operation as much as the set.

The steps of optimizing the main link by performing the main link service can be divided into a clock recovery state (Clock-Recovery, a fixed phase of the clock and data recovery circuit), a channel recovery state (Channel Equalization), a main link stop state, or a normal operation state. Can.

When the main link service is normally completed, the link training process of the auxiliary channel may be started.

In the clock recovery state, a continuous D10.2 pattern can be sent for fast locking of the clock and data recovery circuit.

The D10.2 pattern is a clock-like data and can induce fast fixation of a clock and data recovery circuit.

In the channel compensation state, K28.5, D11.6, and D10.2 patterns can be used.

The receiver 200 may recognize the success of the channel compensation state by recognizing this training pattern.

<Description of the clock restoration status>

The clock recovery state will be described in detail.

The clock recovery state is a state in which it is determined whether the clock and data recovery circuit of the receiving end of the main link is locked.

The clock and data recovery circuit is a circuit for extracting the clock from the transmitted data and restoring data through re-time, in the receiver 200 of a high-speed data communication system such as optical communication, backplane routing, chip-to-chip interconnect It is mainly used to provide the clock necessary to reproduce digital signals.

When transmitting data from the transmitter 100 to the receiver 200, the data signal received from the receiver 200 is out of sync and may be random data including noise components.

For subsequent signal processing, a clock that can be synchronized from NRZ (Non-Return Zero) data must be extracted.

In the clock recovery state, the clock and data recovery circuit extracts the clock from the transmitted data and determines whether the data is normally restored.

After the link training process, if the clock does not recover normally, the differential voltage is adjusted or the bit rate is adjusted to induce the clock to recover normally.

The clock recovery state starts when the transmitter 100 reads the data of the DPCD 300 of the receiver 200, and the transmitter 100 stops pre-emphasis and the minimum differential voltage width (0.4 V diff_pp) to start data transmission.

The transmitter 100 transmits the D10.2 symbol data that is not scrambled through the main link during the link training period to the receiver 200, and when the link training period of about 100us is over, the clock from the DPCD 300 of the receiver 200 and It is possible to read whether the data restoration circuit is locked.

When the clock and data recovery circuit is locked, it moves to the next channel compensation state. If the clock and data recovery circuit is not locked, the differential voltage width is requested.

After the differential voltage width is corrected, the link training process is repeated, and if the clock and data recovery circuit is not locked even after repeating the link training multiple times, the transmission bandwidth may be lowered and the link training process may be repeated.

If the maximum differential voltage width setting value and the minimum reduced bit rate value are met, the link cannot be established and link training is stopped.

<Description of channel compensation status>

Look at the channel compensation status in detail.

The channel compensation state starts after the clock restoration state ends, and K28.5, D11.6, and D10.2 patterns may be repeatedly transmitted in the link training section of the channel compensation state.

In order to inform the training pattern that the display apparatus corresponding to the receiver 200 will receive, the type of the symbol pattern to be transmitted from the main link transmitter 100 to the receiver 100 through the auxiliary channel is transmitted from the transmitter 100 to the receiver 200 The channel compensation state may be started by informing.

The transmitter 100 of the main link starts the pre-emphasis level at 0 and can be adjusted in the order of +3.5dB (1.5x) and 6dB (2x) in the range where the V diff level does not exceed 1.2V. Do.

During the link training process, data transmitted from the transmitter 100 through the main link is compared in the receiver 200, and it can be confirmed whether the bit error rate of about 1E-9 is satisfied.

If a bit error does not occur during the link training process, it becomes a symbol lock state and goes to a normal channel driving state.

Conversely, if the symbol lock is not performed, the channel compensation state process may be repeatedly performed by changing the setting of the pre-emphasis.

If the symbol is not locked despite the repetition, the transmitter 100 lowers the bit rate to perform a link training process.

Even if the link training process is performed by lowering the bit rate, if the symbol is not fixed, the link training process is stopped.

<Description of the normal driving state>

When clock fixation and symbol fixation are achieved, video and audio data are mapped (packing and unpacking, stuffing and un stuffing, framing and unframing, interlane skew and deskew), and data is packetized and lanes of the main link The packet may be unmapped in the receiver 200 by being transmitted through and output an image.

The display port 10 may packetize video and audio data to transmit a data stream.

The main link service has been described so far, and when the main link service is completed, the fourth step, the auxiliary channel link service, is performed.

Hereinafter, the fourth step, the auxiliary channel link service, will be described in detail.

Auxiliary channels, like the main link, require a link training course.

The handshake process for auxiliary channel link training control may use a low-speed interfering method through a Manchester encoding method as in the main link training.

During the link training period, 8B/10B encoded data may be transmitted through the auxiliary channel to determine whether high-speed data transmission on the auxiliary channel is possible.

In the link training process of the auxiliary channel, forward and reverse link training may be performed, respectively.

Before starting link training of the auxiliary channel, the transmitter 100 of the display port 10 may check whether the display device corresponding to the receiver 200 supports the auxiliary channel at high speed.

In the link training of the fast auxiliary channel in each direction, a clock recovery state and a channel compensation state may be performed simultaneously.

Through this process, parameter values and equalizers of the transmitter 100 and the receiver 200 of the high-speed auxiliary channel can be optimized.

As a link training pattern, K28.1+, K27.7-, K28.1-, and K27.7+ control signals are used and can be repeated during the link training period.

The link training sequence is initialized by the transmitter link policy maker 110, and the transmitter link policy maker 110 may perform a process of reading link state information through the auxiliary channel.

If the transmitter link policy maker 110 determines the state of the high-speed auxiliary channel, the link training process starts.

First, a forward link training process is started from a source through a secondary channel to a receiver.

If forward training is successful, a link training process from a receiver to a source is performed.

During the link training process, the read/write process for the DPCD 300 may be performed by the Manchester transmission method.

<Explanation on forward link training>

Hereinafter, the forward link training process will be described.

The high speed auxiliary channel forward channel training process is a process in which the transmitter 100 reads a specific address of the DPCD 300 to determine whether the display device corresponding to the link training pattern, the link training time, and the receiver 200 can use the high speed auxiliary channel. Begins through.

Manchester encoding may be used to transmit control signals for all read and write processes, and 8B/10B encoding may be used in the link training section.

If the display device supports the high-speed auxiliary channel, the voltage swing level and pre-emphasis level of the transmitter 100 are stored in the DPCD 300 to inform the receiver 200 of the current state of the transmitter 100.

Next, in order to inform the pattern information to be transmitted through the high-speed auxiliary channel, the pattern information of the data to be transmitted to the DPCD 300 is stored, and the receiver 200 is also informed whether the scrambler is stopped.

The receiver 200 may transmit an ACK signal to the transmitter 100 whenever it receives a read/write command. After receiving a 0Dh write command in the FAUX_MODE_CTRL area of the DPCD 300, the receiver 200 transmits an ACK signal. After passing it on, it becomes link training status.

When the transmitter 100 receives the ACK signal from the receiver 200, the data encoded by 8B/10B is in a link training state in which the 8B/10B encoded training pattern is transmitted from the transmitter 100 through the high-speed auxiliary channel. 200).

When the link training section is over, the transmitter 100 determines whether the CDR of the receiver 200 is locked and whether the symbol is locked, and if it is locked, performs a reverse link training process and locks If this is not the case, increase the level of pre-emphasis or the voltage swing level and repeat the link training process again, repeat the link training process more than once, and if the link training fails despite multiple link training progress, High-speed auxiliary channels will not be used.

In addition, the link training request unit 500 may transmit a control signal to the HPD so that link training is performed again.

<Description of reverse link training>

Hereinafter, a reverse link training process will be described.

All control of the reverse link training can be controlled by the transmitter link policy maker 110 of the display port 10.

Since data is reversely transmitted from the lower device (sink) of the display port 10 to the upper device (source), the upper device of the secondary channel corresponding to the transmitter 100 of the main link of the display port 10 is the receiver 200 The sub-device corresponding to the receiver 200 of the main link may serve as the transmitter 100.

In the order of the reverse link training process, the link policy maker 110 of the upper device (source) gives the DPCD 300 read command to the link policy maker 210 of the lower device (sink).

The read information reads the differential voltage width and pre-emphasis state of a sink, which acts as a transmitter for a high-speed auxiliary channel in reverse transmission.

After transmitting the 0Dh to the FAUX_MODE_CTRL address of the DPCD 300 to the receiver link policy maker 120 where the transmitter link policy maker 110 transmits data, and receiving the response signal (ACK) signal accordingly, 8B/ through the high speed auxiliary channel The 10B-encoded link training pattern is transmitted from the receiver 200 to the transmitter 100.

After the link training is finished, the transmitter link policy maker 210 issues a DPCD 300 write command to the receiver link policy maker 210.

At this time, in the control signal, Manchester-encoded data is transmitted through the auxiliary channel, and informs the receiver 200 whether the CDR of the transmitter 100 is locked and whether the symbol is locked.

Like forward link training, the link training process can be repeated a number of times, and if the link training fails despite multiple repetitions, the high-speed auxiliary channel cannot be used.

<Link training recovery process description>

As described above, in order to transmit data between the transmitter 100 and the receiver 200, a link training process is important.

The link training process can be applied to both the main link and the auxiliary channel.

Link training is performed when the transmitter 100 and the receiver 200 are initially connected, so that link training of the main link is performed, and then link training of the auxiliary channel can be performed.

When HPDS is generated from HPD during the initial connection between the transmitter 100 and the receiver 200, a case where the first link training fails will be described.

3 is a diagram showing HPDS and link training timing.

Referring to FIG. 3, HPDS generated from HPD is a periodic signal.

Periodic HPDS (PH) may be longer than a maximum link training time (LTTmax) for link training.

The first link training (Link Training 1) may be performed by the toggle signal (toggle 1) of the first HPDS.

When the first link training (Link Training 1) fails, the second link training (Link Training 2) may be performed by the toggle signal (toggle 2) of the second HPDS.

If the second link training (Link Training 2) is successfully performed and successful, the HPDS becomes a high signal and a normal display is possible.

As another example, when HPDS is generated from HPD when the transmitter 100 and the receiver 200 are initially connected, the case where the HPDS is broken due to an external factor will be described.

When the HPDS is broken, since the normal toggle signal is not transmitted to the transmitter 200, the transmitter 200 and the receiver 100 are not recognized as being connected to each other.

This can also be solved by making the HPDS a periodic signal.

4 is a view showing the HPDS and link training timing.

Referring to FIG. 4, HPDS generated from HPD is a periodic signal.

Periodic HPDS (PH) may be longer than a maximum link training time (LTTmax) for link training.

If the toggle of the first HPDS (toggle 1) is broken, the normal link training process is not performed between the transmitter 100 and the receiver 200.

Since the maximum time (LTT) taken when link training is normally performed, since the DPCD 300 does not store information about the result of the link training being successfully performed, the HPD can once again generate HPDS with a toggle. have.

Thus, the transmitter 100 and the receiver 200 may recognize that they are connected to each other by performing the next normal toggle signal (toggle 2), and perform a link training process.

As a method of implementing this, it is assumed that HPDS having a periodicity is generated in HPD.

<First Example>

5 to 7 are views showing a display port.

4 and 5, since HPDS having periodicity occurs in HPD, the first toggle (toggle 1) is broken, so link training is not performed, and the second toggle (toggle 2) indicating a normal waveform is performed. Link training can be performed.

When the link training is normally performed, the transmitter link policy maker 100 reads information from the DPCD 300 of the receiver 200 to read information on which link training is normally performed, and the receiver link policy to prevent the HPDS signal from being output. The signal can be transmitted to the maker 200. At this time, the receiver link policy maker 200 may request that the HPD does not generate a toggle signal. That is, the HPD may request to maintain a high logic signal.

<Second Example>

As another method, referring to FIGS. 4 and 6, when the DPCD 300 is directly connected to the HPD and the HPD is authorized to perform normal link training from the DPCD 300, the HPDS is no longer HPDS. It is possible not to generate a signal.

<Third Example>

As another method, referring to FIGS. 4 and 7, a link training request unit 500 is separately provided to read the results of link training from the DPCD 300 to the link training request unit 500. Can.

When the link training request unit 500 does not read the result of the normal link training from the DPCD 300, the link training request unit (() does not provide any control signal to the HPD generating periodic HPDS. When the 500) reads the result of the link training being normally performed from the DPCD 300, a signal to control the HPD not to output the HPDS may be provided.

Through this method, a connection error that may occur during the initial connection between the transmitter 100 and the receiver 200 is solved, and finally, the transmitter 100 and the receiver 200 are connected to perform link training between each other. It can be done.

On the other hand, after the transmitter 100 and the receiver 200 are initially connected, and after a normal link training process, stream data is normally transmitted from the transmitter 100 to the receiver 200 by internal or external factors. Synchronization may be broken between the 100 and the receiver 200.

<First Example>

3 and 5, the transmitter link policy maker 110 reads that clock fixing and symbol fixing are not formed from the DPCD 300, and provides it to the receiver link policy maker 210 to provide the receiver link policy. The maker 210 may allow the HPDS to be output from the HPD. In addition, since HPDS is a signal that periodically forms a toggle, link training may be repeatedly performed until link training is successful, so that link training may be finally achieved.

Otherwise, if link training is successful, the successful result of link training is stored in the DPCD 300, and the receiver link policy maker 210 reads the result of link training success from the DPCD 300, and the receiver link policy maker 210 may request the HPD to request that the HPD does not generate a toggle signal.

<Second Example>

Referring to FIGS. 3 and 6, when synchronization between the transmitter 100 and the receiver 200 is broken during a normal data transmission process, in the state where the DPCD 300 and the HPD are electrically directly connected, the HPD is the DPCD ( It reads from 300) that clock fixation and symbol fixation are not formed, and can output HPDS having periodicity. In addition, when the result of normal link training is authorized, the HPDS signal may not be generated any more.

<Third Example>

3 and 7, when synchronization between the transmitter 100 and the receiver 200 is broken during a normal data transmission process, the DPCD 300 fixes the link clock between the transmitter 100 and the receiver 200 And symbol fixation is not formed, and the link training request unit 500 reads it, and outputs a control signal to the HPD so that the HPD outputs HPDS.

In this case as well, the HPDS can be a periodic signal, so synchronization between the transmitter and the receiver is broken during data transmission, so that link training is repeatedly performed until link training between the transmitter and the receiver is normally performed. Can.

<Fourth Example>

8 is a view showing the signal of the HPDS.

Referring to FIG. 8, the HPDS was previously described as a periodic signal. Alternatively, in the HPDS, the time interval between the first toggle and the N (N is an integer) th toggle can be gradually increased. .

Specifically, the time interval between the first toggle (toggle 1) and the second toggle (toggle 2) is PH1, the time interval between the second toggle (toggle 2) and the third toggle (toggle 3) is PH2, and the third toggle ( When the time interval between toggle 3) and the fourth toggle (toggle 4) is PH3, a relationship of PH1<PH2<PH3 can be established.

9 is a diagram showing link training timing between HPDS and a plurality of transmitters and a single number of receivers.

Referring to FIG. 9, when one of the plurality of transmitters (Device 1 and 2) is connected to the receiver 200, normal link training can be performed.

Specifically, the link training time with the receiver 200 may be different depending on the transmitter 100 selected.

8, the signal may be configured as shown in FIG. 8, so that even if any transmitters (Devices 1 and 2) are connected to the receiver 200, link training may be finally performed.

For example, in the case of the first transmitter (Device 1), since the period (PH) of the HPDS is longer than the maximum time for link training (LTT1) of the first transmitter, if the initial link training (LT1) fails, the second after a certain time Link training (LT2) may be performed again.

If the second and third link training (LT2, LT3) also fails, a toggle signal (Toggle 4, 5) is generated until success and the link training (LT4, LT5) can be repeatedly executed.

However, in the case of the second transmitter (Device 2), since the period (PH) of the HPDS is shorter than the maximum link training time (LTT2) between the second transmitter (Device 2) and the receiver 200, the second transmitter (Device 2) and the receiver In the link training process of 200, a request to perform the link training process again, that is, the second link training LT2 may be performed.

At this time, a second link training (LT2) process is performed again, and a signal is formed so that the third link training (LT3) process is performed (toggle 3) during the second link training (LT2) process, and the third link training ( LT3) Although the process is performed, since the time interval between toggles of the HPDS becomes longer as time passes, the link training process is normally performed between the second transmitter (Device 2) and the receiver 200 by the fourth toggle signal (Toggle 4) signal. (LT4). In addition, even if the fourth link training process LT4 fails, the fifth link training process LT5 is performed after a certain period of time, and finally, the link training is successful, thereby enabling normal data transmission.

On the other hand, if the link training request unit of the receiver 200 fails even if the link training process for using the high-speed auxiliary channel is repeatedly executed a predetermined number of times, the failed information is read from the DPCD 300, and HPDS can be regenerated in HPD. I can make it.

In this case, the link training process for using the fast auxiliary channel may be performed again.

The link training request unit 500 may cause a toggle HPD signal (HPDS) to be generated to re-execute the main link training process when the main link training process fails, and the link for the high-speed auxiliary channel after the main link training process ends. If a training process is required, the link training process for the high-speed sentry channel is performed, and in this case, the link training for the high-speed sentry channel can be performed again from the beginning if the link training for the high-speed sentry channel fails. It can generate HPD signals.

In the detailed description of the present invention described above, the present invention has been described with reference to preferred embodiments of the present invention, but those skilled in the art or those skilled in the art will appreciate the invention described in the claims below. It will be understood that various modifications and changes may be made to the present invention without departing from the spirit and technical scope. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

10 Displayport
100 transmitter, source device, source
110 transmitter link polish maker
120 transmitter stream polish maker
130 stream source
200 receivers, sink unit, sink
210 Receiver Link Polish Maker
220 receiver stream polish maker
230 stream sink
300 DPCD
400 EDID
500 Link Training Request

Claims (20)

As a data transmission method of a display port composed of a transmitter and a receiver and a link composed of a main link, a secondary channel, and a Hot Plug Detect (HPD),
A device service step of determining whether to transmit stream data from the transmitter to the receiver; And
And a link service step of performing link training to optimize the state of the link by using a toggle signal by the HPD,
The link service step includes forming a link clock lock and a symbol lock,
The toggle signal is repeatedly generated by the HPD until the link training is successful, and the data transmission method of DisplayPort that is not generated when the link training is successful.
According to claim 1,
And recognizing an initial connection between a transmitter and a receiver using the toggle signal.
According to claim 2,
The transmitter includes a transmitter link policy maker, a transmitter stream policy maker and a transmitter stream source,
The receiver includes a receiver link policy maker, a receiver stream policy maker and a receiver stream source, DisplayPort Configuration Data (DPCD) and Extended Display Identification Data (EDID),
The step of recognizing the connection between the transmitter and the receiver using the toggle signal includes the step of the transmitter link policy maker receiving the toggle signal and informing the transmitter stream policy maker that a sink device is connected,
In the device service step, the transmitter stream policy maker reads information about the display device from the receiver stream policy maker and the EDID through a read operation of the EDID, and compares information of the main stream attribute data and the info-frame data generator. Including steps,
The link service step
The transmitter link policy maker reading the data of the DPCD to start the link training; And
And restoring a clock by transmitting a predetermined pattern from the transmitter to the receiver.
According to claim 3,
The receiver further includes a link training request unit,
The link training request unit,
A method of transmitting data from DisplayPort that reads link training success information from the DPCD and applies a control signal to the HPD so that the toggle signal is not generated.
According to claim 3,
If the above link training is successful,
Storing the result of the successful link training in the DPCD,
The transmitter link policy maker reads the link training success result from the DPCD, and
And the transmitter link policy maker requesting the receiver link policy maker to prevent the toggle signal from being generated.
According to claim 3,
If the above link training is successful,
Storing the success result of the link training in the DPCD,
The receiver link policy maker reads the result of successful link training from the DPCD, and
The receiver link policy maker further comprises the step of requesting the HPD so that the toggle signal is not generated.
The method according to any one of claims 4 to 6,
The toggle signal is a data transmission method of a display port having a low (Low) logic.
The method of claim 7,
When the link training is successful, a signal transmitted by the HPD maintains high logic.
According to claim 1,
The toggle signal is a display port data transmission method that occurs at a predetermined period until the link training is successful.
The method of claim 9,
The period in which the toggle signal is generated is a display port data transmission method longer than the time it takes to perform the link training.
According to claim 1,
The first to Nth (N is an integer) th toggle signal is sequentially generated by the HPD,
The time interval between adjacent toggle signals increases as the first to Nth toggle signals move, and the display port transmits data.
According to claim 1,
The link service step,
A display port data transmission method comprising a main link service step and a secondary channel link service step.
According to claim 1,
And transmitting an isochronous data stream from the transmitter to the receiver using the link configured by the link training.
A transmitter and a receiver, and a link connecting the transmitter and the receiver,
The link is composed of a main link, an auxiliary channel and HPD (Hot Plug Detect),
The transmitter and the receiver perform link training to form a link clock lock and a symbol lock between the transmitter and the receiver using a toggle signal by the HPD,
The toggle signal is a display port repeatedly generated until the link training is successful.
The method of claim 14,
The display port in which the toggle signal is generated is longer than the time it takes to perform the link training.
The method of claim 14,
The first to Nth (N is an integer) th toggle signal is sequentially generated by the HPD,
A display port in which a time interval between adjacent toggle signals increases as the first to Nth toggle signals move.
The method of claim 14,
The transmitter includes a transmitter link policy maker that manages the link,
The receiver includes a receiver link policy maker and DisplayPort Configuration Data (DPCD) that stores information about the state of the link,
The transmitter link policy maker reads the success result of the link training from the DPCD and requests the receiver link policy maker to prevent the toggle signal from being generated.
The method of claim 14,
The receiver includes a receiver link policy maker and DisplayPort Configuration Data (DPCD) that stores information about the state of the link,
The receiver link policy maker reads the success result of the link training from the DPCD to control the HPD so that the toggle signal is not generated.
The method of claim 14,
The receiver includes a DisplayPort Configuration Data (DPCD) and a link training request unit storing information on the state of the link,
The link training request unit reads the success result of the link training from the DPCD to control the HPD so that the toggle signal is not generated.
The method of claim 14,
The receiver includes a DisplayPort Configuration Data (DPCD) and a link training request unit storing information on the state of the link,
The link training request unit reads a result of a broken link clock or symbol lock between the transmitter and the receiver from the DPCD to control the HPD so that the toggle signal is generated.

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