阅读说明：本技术 面板自刷新后的时序重新同步方法 (Timing sequence resynchronization method after panel self-refreshing ) 是由 郭思尧 于 2020-07-02 设计创作，主要内容包括：本发明公开了一种面板自刷新后的时序重新同步方法,应用于发送端信号与接收端信号之间的时序重新同步。时序重新同步方法包含下列步骤：(a)当面板需离开自刷新状态时,启动时序重新同步；(b)等待接收端信号的下降沿；(c)决定时序重新同步的时序重新同步策略；(d)接收端信号根据时序重新同步策略输出下一帧；(e)判断接收端信号与发送端信号的垂直空白区间是否彼此对齐；以及(f)若步骤(e)的判断结果为是,则结束时序重新同步。(The invention discloses a timing sequence resynchronization method after panel self-refreshing, which is applied to timing sequence resynchronization between a signal at a sending end and a signal at a receiving end. The timing resynchronization method comprises the following steps: (a) when the panel needs to leave the self-refreshing state, the timing sequence is started to be resynchronized; (b) waiting for the falling edge of the signal of the receiving end; (c) determining a timing resynchronization strategy for timing resynchronization; (d) the receiving end signal outputs the next frame according to the timing sequence resynchronization strategy; (e) judging whether vertical blank intervals of a receiving end signal and a sending end signal are aligned with each other or not; and (f) if the judgment result in the step (e) is yes, ending the timing resynchronization.)

1. A method for timing resynchronization after panel self-refresh, which is applied to a timing resynchronization between a sending end signal and a receiving end signal, is characterized by comprising the following steps:

(a) when a panel needs to leave the self-refreshing state, the timing sequence is started to be resynchronized;

(b) waiting for a falling edge of the receiving end signal;

(c) determining a timing resynchronization strategy for the timing resynchronization;

(d) the receiving end outputs the next frame according to the time sequence resynchronization strategy;

(e) judging whether the vertical blank intervals of the receiving end signal and the transmitting end signal are aligned with each other; and

(f) if the judgment result in the step (e) is yes, ending the timing resynchronization.

2. The method of claim 1, further comprising the steps of:

(g) if the judgment result in the step (e) is negative, judging whether a pixel clock of the sending end signal is changed.

3. The method of claim 2, wherein if the determination result in step (g) is yes, then returning to step (b).

4. The method of claim 2, wherein if the determination result in step (g) is negative, then returning to step (d).

5. The timing resynchronization method according to claim 1, wherein step (e) determines that the vertical blanking intervals of the receiver signal and the transmitter signal are aligned with each other according to the alignment of the rising edge of the receiver signal and the rising edge of the transmitter signal.

6. The timing resynchronization method according to claim 1, wherein step (e) determines that the vertical blanking intervals of the receiver signal and the transmitter signal are aligned with each other according to the alignment of the falling edge of the receiver signal and the falling edge of the transmitter signal.

7. The method of claim 1, wherein step (a) is performed by knowing that the panel is in a self-refresh state when a self-refresh stop packet is received.

8. The timing resynchronization method of claim 1, wherein step (c) determines the timing resynchronization strategy to minimize the number of frames required to complete the timing resynchronization on the premise that a plurality of required constraints on the panel are met.

9. The method of claim 8, wherein the plurality of constraints comprise: satisfying a highest frame rate, a lowest frame rate, a minimum vertical blanking interval and a highest pixel clock supported by the panel.

10. The method of claim 1, wherein step (c) comprises calculating at least one timing resynchronization parameter.

11. The method of claim 10, wherein the at least one timing resynchronization parameter comprises: in the process of completing the timing resynchronization, the number of frames that the sending end signal needs to transmit, the length of the vertical blank interval, the length of the vertical start interval and the frame rate.

Technical Field

The present invention relates to Timing resynchronization (Timing resynchronization), and more particularly, to a Timing resynchronization method after a panel self-refresh.

Background

Referring to fig. 1, fig. 1 is a schematic diagram of a conventional embedded display port (eDP) system architecture 1. For example, in a conventional notebook computer, the sending end (Source) TX of the embedded display port system 1 may be a Graphics Processing Unit (GPU) and the receiving end (Sink) RX thereof may be a Timing Controller (Timing Controller) TCON. The timing controller TCON further includes a Remote Frame Buffer (RFB) and is coupled to the panel (including the display driver IC) PL, but not limited thereto.

Generally, after the panel PL completes the self-refresh operation, the Frame timing (Frame timing) of the receiving end signal and the sending end signal are not synchronized, so that a re-synchronization (Resynchronization) operation is required to align the Vertical blanking intervals (Vertical blanking) of the receiving end signal and the sending end signal, so as to synchronize the Frame timing of the receiving end signal and the sending end signal. However, during the timing re-synchronization, some frames in the transmitting signal may be lost and not present in the receiving signal, such as the sixth frame F6 in fig. 2.

As shown in fig. 2, the receiving end signal usually achieves timing resynchronization by adjusting a Frame rate (Frame rate), a Vertical blanking interval (Vertical blanking), or a Total Vertical time (Total Vertical time).

For example, during the timing resynchronization, the receiving end signal may use a fixed ratio of k% to increase the total vertical time, as shown in equation 1:

the total vertical time Sink _ Vtotal of the receiving end signal is the total vertical time Source _ Vtotal (1+ k%) of the transmitting end signal (formula 1)

If the receiving end signal requires at most N frames of the transmitting end signal to complete the resynchronization, N is 100/k.

It should be noted that, when the frame rate of the receiving end signal output is higher than the highest frame rate supported by the panel, it is likely to result in insufficient charging time in one frame; when the frame rate of the signal output from the receiving end is lower than the lowest frame rate supported by the panel, it is likely that the discharge in one frame is too much to cause image Flicker (Flicker). Therefore, in order to avoid the above problem, during the timing re-synchronization, the frame rate of the receiving-end signal output to the panel display driving IC still needs to meet the limitations of the lowest frame rate and the highest frame rate supported by the panel.

In addition, in the process of timing resynchronization, if the receiving end signal adopts a mode of shortening a Vertical blanking interval (Vertical blanking), the receiving end signal also needs to meet the condition of the shortest Vertical blanking interval supported by the system; if the receive-side signal is to shorten the Vertical active interval (Vertical active), it also meets the condition of the highest Pixel clock (Pixel clock) supported by the system.

In practical applications, the sending-end signal is not necessarily changed from the low frame rate to the high frame rate (e.g. from 40Hz to 60Hz) before and after the timing resynchronization, but may also be changed from the high frame rate to the low frame rate (e.g. from 60Hz to 40Hz), or the same frame rate is maintained before and after the resynchronization (e.g. the same frame rate is maintained at 60Hz), depending on the actual situation.

It should be noted that, since the above-mentioned limitations regarding timing resynchronization are all important, if the above-mentioned limitations are considered at the same time, it is likely that the timing resynchronization takes too long (i.e. the number of frames transmitted by the sender to complete the timing resynchronization is too large).

If Extended Display Identification Data (EDID) of the panel lists that the supported frequency range is 40Hz to 60Hz, the actually supportable frame rate range is usually only slightly wider than the range of 40Hz to 60Hz (for example, the range of 37Hz to 63 Hz).

In practical applications, if the frame rate at the receiving end needs to be decreased from a high frame rate (e.g. 60Hz) to a low frame rate (e.g. 40Hz) during the process from self-refresh to timing resynchronization, once the receiving end performs timing resynchronization by increasing the vertical blank space or the total vertical time, the frame rate may not be able to be decreased below 37Hz, which may cause the number of frames transmitted by the transmitting end required for timing resynchronization to be too many (e.g. if k in formula 1 is 8, the transmitting end needs to transmit 13 frames at most to complete resynchronization), resulting in poor efficiency. The above problems remain to be overcome.

Disclosure of Invention

In view of the above, the present invention provides a method for resynchronization of a self-refreshed timing sequence of a panel, so as to effectively solve the above-mentioned problems encountered in the prior art.

The timing sequence resynchronization method after the panel self-refreshing is suitable for a timing sequence controller under a frequency conversion framework, can reduce the frame number required by the timing sequence resynchronization process of a sending end (Source) and a receiving end (Sink) to the minimum, thereby improving the response speed of the panel self-refreshing, avoiding the loss of continuity when the panel displays a dynamic picture due to the frame rate reduction in the timing sequence resynchronization process, and also meeting the limitation of the frame number which can be transmitted to the receiving end by the sending end during the resynchronization period in practice.

An embodiment of the present invention is a method for timing resynchronization after panel self-refresh. In this embodiment, the timing resynchronization method is applied to timing resynchronization between a Source signal and a Sink signal. The timing resynchronization method comprises the following steps: (a) when the panel needs to leave the self-refreshing state, the timing sequence is started to be resynchronized; (b) waiting for the falling edge of the signal of the receiving end; (c) determining a timing resynchronization strategy for timing resynchronization; (d) the receiving end outputs the next frame according to the timing sequence resynchronization strategy; (e) judging whether vertical blank intervals of a receiving end signal and a sending end signal are aligned with each other or not; and (f) if the judgment result in the step (e) is yes, ending the timing resynchronization.

In one embodiment, the timing resynchronization method further comprises the following steps: (g) and (e) if the judgment result in the step (e) is negative, judging whether the Pixel clock (Pixel clock) of the signal at the transmitting end is changed.

In one embodiment, if the determination result in the step (g) is yes, the step (b) is returned to.

In one embodiment, if the determination result in the step (g) is negative, the step (d) is returned to.

In one embodiment, the step (e) determines that the vertical blanking intervals of the receiving-end signal and the transmitting-end signal are aligned with each other according to the alignment of the rising edge of the receiving-end signal and the rising edge of the transmitting-end signal.

In one embodiment, the step (e) determines that the vertical blanking intervals of the receiving-end signal and the transmitting-end signal are aligned with each other according to the fact that the falling edge of the receiving-end signal and the falling edge of the transmitting-end signal are aligned with each other.

In one embodiment, the step (a) is to know that the panel needs to leave the self-refresh state when the self-refresh stop packet is received.

In one embodiment, step (c) determines the timing resynchronization strategy to minimize the number of frames required to complete the timing resynchronization on the premise that a plurality of required constraints associated with the panel are satisfied.

In one embodiment, the plurality of required constraints includes: the Frame rate, the Vertical blanking interval and the Pixel clock supported by the panel are all satisfied.

In one embodiment, step (c) includes calculating at least one timing resynchronization parameter.

In one embodiment, the at least one timing resynchronization parameter comprises: and in the process of completing the timing resynchronization, the frame number of the signals needing to be transmitted by the transmitting end, the length of the vertical blank interval, the length of the vertical starting interval and the frame rate.

The advantages and spirit of the present invention can be further understood by the following detailed description of the invention and the accompanying drawings.

Drawings

FIG. 1 is a diagram illustrating a conventional embedded display Port (eDP) system architecture.

Fig. 2 is a timing diagram illustrating a timing re-synchronization process between a transmitting signal and a receiving signal.

FIG. 3 is a flowchart illustrating a timing resynchronization method according to an embodiment of the present invention.

Fig. 4A to 4C are timing diagrams respectively illustrating that when the frame rate of the receiving end signal is less than that of the transmitting end signal during the timing synchronization, the number of frames transmitted by the transmitting end signal required for completing the timing resynchronization is 1 to 3.

Fig. 5A to 5C are timing diagrams respectively illustrating that when the frame rate of the receiving-end signal is greater than that of the transmitting-end signal during the timing synchronization, the number of frames transmitted by the transmitting-end signal required for completing the timing resynchronization is 1 to 3.

Description of the main element symbols:

S10-S22

1 Embedded display Port (eDP) system architecture

GPU (graphics processing Unit) graphics processor

TCON time schedule controller

PL Panel

TX transmitting terminal

RX receiving end

RFB remote frame buffer

F1-F7 first to seventh frames

T1-T2 first time-second time

The length of the interval from the falling edge of the first frame receiving end signal to the falling edge of the sending end signal after the x enters the time sequence resynchronization

y enters the interval length from the rising edge of the first frame sending end signal to the falling edge of the receiving end signal after the timing sequence is resynchronized

a vertical start interval of sending terminal

b vertical blank interval of transmitting terminal

A receiving end vertical starting interval

B receiving end vertical blank interval

Detailed Description

Reference will now be made in detail to exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. The same or similar numbered elements/components used in the drawings and the embodiments are used to represent the same or similar parts.

An embodiment according to the present invention is a timing resynchronization method. In this embodiment, the timing resynchronization method is applied to panel self-refresh, and is used to achieve timing resynchronization between a sending end (Source) and a receiving end (Sink) within a minimum number of frames, but not limited thereto.

Referring to fig. 3, fig. 3 is a flowchart illustrating a timing resynchronization method in this embodiment. As shown in fig. 3, the method for timing resynchronization between a receiver signal and a transmitter signal may comprise the following steps:

step S10: when receiving the self-refreshing stopping package, starting timing resynchronization;

step S12: waiting for a Falling edge (Falling edge) of the signal at the receiving end;

step S14: determining a timing resynchronization strategy (calculating a timing resynchronization parameter);

step S16: the receiving end outputs the next frame according to the timing sequence resynchronization strategy;

step S18: judging whether the Rising edge (Rising edge)/Falling edge (Falling edge) of the receiving end signal and the sending end signal are aligned with each other or not;

if the determination result in the step S18 is yes, it represents that the timing resynchronization between the receiving end signal and the sending end signal is completed, so the method performs the step S20 to end the timing resynchronization;

if the determination result in the step S18 is "no", which indicates that the timing resynchronization between the receiving end signal and the transmitting end signal is not completed yet, the method performs step S22: judging whether a Pixel clock (Pixel clock) of a sending end is changed or not;

if the determination result of the step S22 is yes, the method returns to the step S12 again; and if the determination result of the step S22 is no, the method returns to the step S16.

In step S14, the timing resynchronization method of the present invention is to effectively minimize the number of frames required for completing the timing resynchronization between the sender-side signal and the receiver-side signal on the premise of satisfying at least the following constraints:

(1) satisfying the highest frame rate and the lowest frame rate supported by the panel;

(2) satisfying the minimum Vertical blanking interval (Vertical blanking) supported by the system; and

(3) the highest Pixel clock (Pixel clock) supported by the system is satisfied.

In step S14, the timing resynchronization method of the present invention uses a consistent calculation method to determine at least the following strategies taking into account at least the following parameters:

(1) in the process of completing the timing resynchronization, the frame number of the signals to be transmitted of the sending end;

(2) the length of a Vertical blank interval (Vertical blanking) and a Vertical start interval (Vertical active) in the timing resynchronization process; and

(3) the frame rate during the timing resynchronization process (whether the frame rate of the signal at the transmitting end is the highest frame rate or the lowest frame rate, is considered).

In step S22, even if the Pixel clock (Pixel clock) of the sender signal changes (i.e. the M/N value in the MSA data sent from the sender of the embedded display port (eDP) changes), the receiver signal only needs to recalculate to determine a new timing resynchronization strategy to cope with the change.

In practical applications, the timing resynchronization strategy may include, but is not limited to, adjusting the length of the vertical blanking interval or adjusting the pixel clock of the output signal of the receiving end (which is equivalent to adjusting the length of the vertical start interval).

Next, different methods applied to the condition that the frame rate of the receiving-side signal is lower than that of the transmitting-side signal and the condition that the frame rate of the receiving-side signal is higher than that of the transmitting-side signal will be described.

Method 1 (when the frame rate of the receiving end signal is less than that of the transmitting end signal in the time sequence synchronization process)

Referring to fig. 4A to 4C, fig. 4A to 4C respectively show timing diagrams of the frames transmitted by the sending-end signal for completing the timing resynchronization when the frame rate of the receiving-end signal is less than the frame rate of the sending-end signal in the timing synchronization process is 1 to 3.

As shown in fig. 4A, when the frame rate of the receiving end signal is less than the frame rate of the sending end signal in the process of timing synchronization, if the sending end signal only needs to transmit 1 frame to successfully complete timing resynchronization between the sending end signal and the receiving end signal, the synchronization strategy of the receiving end signal can be obtained by adjusting the length of the vertical blank interval to B, where B is x + B, where x is the length of the interval from the falling edge of the first frame of the receiving end signal to the falling edge of the sending end signal after the timing resynchronization is entered.

As shown in fig. 4B, when the frame rate of the receiving end signal is less than the frame rate of the sending end signal in the process of timing synchronization, if the sending end signal needs to transmit 2 frames to complete timing resynchronization between the sending end signal and the receiving end signal, it can be obtained that the synchronization strategy of the receiving end signal is to adjust the length of the vertical blank interval to B and the length of the vertical start interval of the receiving end signal to a, and a +2B is x + a +2B, where x is the length of the interval from the falling edge of the first frame of the receiving end signal to the falling edge of the sending end signal after the timing resynchronization is entered.

As shown in fig. 4C, when the frame rate of the receiving end signal is less than the frame rate of the sending end signal in the process of timing synchronization, if the sending end signal needs to transmit 3 frames to complete timing resynchronization between the sending end signal and the receiving end signal, the synchronization strategy of the receiving end signal can be obtained by adjusting the length of the vertical blank interval to B and the length of the vertical start interval of the receiving end signal to a, and 2A +3B is x +2A +3B, where x is the interval length from the falling edge of the first frame of the receiving end signal to the falling edge of the sending end signal after the timing resynchronization is entered.

By analogy, when the frame rate of the receiving end signal is less than that of the sending end signal in the process of sequence synchronization, if the sending end signal needs to transmit N frames (N is a positive integer) to complete the sequence resynchronization between the sending end signal and the receiving end signal, the synchronization strategy of the receiving end signal can be obtained by adjusting the length of the vertical blank interval to be B and the length of the vertical start interval of the receiving end signal to be a, so that formula 2 can be obtained:

(N-1) A + NB + x + (N-1) a + Nb (equation 2)

Wherein, x is the interval length from the falling edge of the first frame receiving end signal to the falling edge of the sending end signal after the time sequence resynchronization is started.

Method 2 (when the frame rate of the receiving end signal is larger than that of the transmitting end signal in the time sequence synchronization process)

Referring to fig. 5A to 5C, fig. 5A to 5C respectively show timing diagrams of the transmitting end signals with frame numbers 1 to 3 for completing the timing resynchronization when the frame rate of the receiving end signal is greater than the frame rate of the transmitting end signal in the timing synchronization process.

As shown in fig. 5A, when the frame rate of the receiving end signal is greater than the frame rate of the sending end signal in the process of timing synchronization, if the sending end signal only needs to transmit 1 frame to successfully complete timing resynchronization between the sending end signal and the receiving end signal, the synchronization strategy of the receiving end signal can be obtained by adjusting the length of the vertical blank interval to B and the length of the vertical start interval of the receiving end signal to a, and a + B is x, where x is the length of the interval from the falling edge of the first frame of the receiving end signal to the falling edge of the sending end signal after the timing resynchronization is entered.

As shown in fig. 5B, when the frame rate of the receiving end signal is greater than the frame rate of the sending end signal in the process of timing synchronization, if the sending end signal needs to transmit 2 frames to complete timing resynchronization between the sending end signal and the receiving end signal, the synchronization strategy of the receiving end signal can be obtained by adjusting the length of the vertical blank interval to B and the length of the vertical start interval of the receiving end signal to a, and 2A +2B is x + a + B, where x is the length of the interval from the falling edge of the first frame of the receiving end signal to the falling edge of the sending end signal after the timing resynchronization is entered.

As shown in fig. 5C, when the frame rate of the receiving end signal is greater than the frame rate of the sending end signal in the process of timing synchronization, if the sending end signal needs to transmit 3 frames to complete timing resynchronization between the sending end signal and the receiving end signal, the synchronization strategy of the receiving end signal can be obtained by adjusting the length of the vertical blank interval to B and the length of the vertical start interval of the receiving end signal to a, and 3A +3B is x +2a +2B, where x is the interval length from the falling edge of the first frame of the receiving end signal to the falling edge of the sending end signal after the timing resynchronization is entered.

By analogy, when the frame rate of the receiving end signal is greater than that of the sending end signal in the process of sequence synchronization, if the sending end signal needs to transmit N frames (N is a positive integer) to complete the sequence resynchronization between the sending end signal and the receiving end signal, the synchronization strategy of the receiving end signal can be obtained by adjusting the length of the vertical blank interval to be B and the length of the vertical start interval of the receiving end signal to be a, so that formula 3 can be obtained:

n (a + B) ═ x + (N-1) (a + B) (equation 3)

Wherein, x is the interval length from the falling edge of the first frame receiving end signal to the falling edge of the sending end signal after the time sequence resynchronization is started.

It should be noted that, for the above method 1, the following is further detailed:

in the method 1, although the frame rate of the receiver signal is lower than that of the transmitter signal during the timing resynchronization, the frame rate of the receiver signal still cannot be lower than the lowest frame rate allowed by the panel, i.e. the frame rate of the receiver signal is not without a lower limit. From equation 2 above, equation 4 can be derived as follows:

wherein, Sink _ VTotal represents the total vertical time of the receiving end signal; source _ VTotal represents the total vertical time of the transmit-end signal; sink _ VActive represents a vertical starting interval of a receiving end signal; source _ VActive represents a vertical start interval of a transmitting-end signal.

In addition, when the frame rate of the receiving end signal is to be reduced (the total vertical time is increased), the frame rate can be reduced by increasing the length of the vertical blank interval or the vertical start interval. However, since adjusting the vertical start interval of the receiver signal enables the receiver signal to use a different pixel clock than the transmitter signal, and does not provide any significant advantage or effect, the present invention preferably increases the length of the vertical blank interval of the receiver signal (i.e. B), and makes the vertical start interval Sink _ VActive of the receiver signal equal to the vertical start interval Source _ VActive of the transmitter signal (i.e. a).

Wherein, x is the length of the interval from the falling edge of the receiving end signal to the falling edge of the transmitting end signal of the first frame after the time sequence resynchronization is started. From equation 5, it can be seen that the timing synchronization strategy under this condition is to increase the vertical blanking interval Sink _ VBlank, where the increased length is x/N, that is, the smaller the number of frames N sent by the sending end in the timing synchronization process, the larger the length of the vertical blanking interval needed to complete the timing synchronization.

It should be noted that, for the above method 2, the following is further detailed:

in the method 2, although the frame rate of the receiver signal is greater than that of the transmitter signal during the timing resynchronization, the frame rate of the receiver signal cannot be higher than the highest frame rate allowed by the panel, i.e. the frame rate of the receiver signal is not without an upper limit. From equation 3 above, equation 6 can be derived as follows:

in practical applications, the method 2 can be further divided into a method 2(a) and a method 2(b), which are described as follows:

method 2 (a): only the length of the vertical blanking interval of the receiver signal is shortened (i.e., B), and the lengths of the vertical start intervals of the receiver signal and the transmitter signal are maintained to be equal (i.e., a ═ a), as shown in equation 7:

and y is the interval length from the rising edge of the first frame sending end signal to the falling edge of the receiving end signal after the time sequence resynchronization is started. From equation 7, it can be seen that the timing synchronization strategy under this condition is to shorten the vertical blanking interval Sink _ VBlank by a length (b + y)/N, that is, the smaller the number of frames N sent by the sending end in the timing synchronization process, the larger the length of the vertical blanking interval needed to be reduced for completing the timing synchronization. It should be noted that the length B of the vertical blank interval of the receiving-end signal cannot be smaller than the minimum vertical blank interval allowed by the system.

Method 2 (b): the total vertical time length of the receiver signal (i.e. a + B) is shortened, i.e. the length a of the vertical start interval of the receiver signal and the length B of the vertical blank interval of the receiver signal are adjusted simultaneously, as shown in equation 8:

from equation 8, it can be seen that the timing synchronization strategy under this condition is to shorten the total vertical interval Sink _ VTotal by (b + y)/N, i.e. the smaller the number of frames N sent by the sender during the timing synchronization, the larger the length of the total vertical interval needed to complete the timing synchronization. It should be noted that when the length a of the vertical start interval of the receiving end signal is shortened, a higher pixel clock is required but cannot be higher than the highest pixel clock allowed by the Timing Controller (TCON).

Compared with the prior art, the panel self-refreshed time sequence resynchronization method provided by the invention can be suitable for a time sequence controller under a frequency conversion architecture, not only can reduce the frame number required by the time sequence resynchronization process of the sending end and the receiving end to the minimum, thereby improving the response speed of the panel from the self-refreshing state to the instant display state, but also can avoid the loss of continuity when the panel displays dynamic pictures due to the reduction of the frame rate of the sending end in the time sequence resynchronization process, and also can meet the limitation of the frame number which can be transmitted to the receiving end by the sending end during the resynchronization period in practice.