This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

PROCESSOR-SDK-DRA7X: Display Flicker Part 3

Part Number: PROCESSOR-SDK-DRA7X

Hello TI team, 

ISSUE: DISPLAY FLICKER OBSERVED

Previous Reference 

Ticket: https://e2e.ti.com/support/processors/f/791/t/889397

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/946368/compiler-processor-sdk-dra7x-display-flicker

Usecase

Path: vision_sdk/apps/src/rtos/usecases/weston_dualcamera_dsswb

UseCase: weston_dualcamera_dsswb


Capture -> Display_Video
Capture_1 -> Display_Video1
DispDistSrc_gfx -> Display_gfx
DispDistSrc_vid3 -> Display_vid3
Capture_dsswb -> Alg_SwCrc

Background: Previously we have observed DisplayFlicker in HU, but after switching to HDMI clock, we

did not observe this issue. (Switching to HDMI clock- Please see Reference Ticket). 

Current Situation: On Bootup we see HU is flickering and recovering after a short while. Issue is 

                               seen randomly and it is not always issue.

Already Verified Below in the Last Debugging session:

1.  There is no Sync Loss verified

2.  Setting DSS high priority still we are seeing issue. 

Best Regards,

RK

Best Regards,

Raghu Kadari

  • Hi RK,

    The previous tickets were from some time back.   Has anything changed in the system under test, recently, that would cause the "Current Situation" to occur (new S/W modifications, new board, etc )?  Or has this boot up flicker been present the whole time?

    Thanks,

    kb

  • Hi KB, 


    Note: Bootup Flicker is  occurring only in few units not in all units and issue is observed sometimes (Not ALWAYS). 

    Bootup Flicker is present whole time and there has been no change that has gone in. 

     We can have short sync up to so that we are on same page, please let me know

    BR,

    RK

  • Hi RK,

    Had a quick sync on the TI side on this issue, and wanted to confirm/understanding the following:

    1) The HDMI PLL is now being used, where previously it had been VID1/2 PLL.   Where in the boot flow / initialization  is the HDMI PLL being programmed / selected.   Could the flicker be a result of the switch to the HDMI PLL?

    2) Is the dssDispcMflagParam.globalMflagCtrl value being set to 1, in displayCtrlLink.c.   Is the flicker being seen as a result of this flag being set?

    Essentially, review the overall boot sequence and look for any display related programming that could be, being done ,while the display is active.

    Thanks,

    KB

  • Hi KB,

    First Display Flicker Occurence:
    Initially Flicker was occuring randomly and for short time and recovering. We use to
    see this issue frequently when HIGH resolution videos are played.

    FIX:
    During this time, VID1 PLL was used, after shifting to HDMI PLL, this issue was resolved.
    This is also doubled confirmed with some lifetime stress testing.


    Current ISSUE - DISPLAY FLICKER:
    The current Display Flicker is observed only after Bootup for short time and is recovering.
    and it is observed not in all units but only in few HU's (Test Vehicles)


    HDMI PLL:

    - System will first will send command to boot M4 and then to linux (A15)

    - Usecase
    Capture -> Display_Video
    Capture_1 -> Display_Video1
    DispDistSrc_gfx -> Display_gfx
    DispDistSrc_vid3 -> Display_vid3
    Capture_dsswb -> Alg_SwCrc

    In Create state of the usecase (above), we trigger HDMI Clock selection via
    ChainsCommon_SetDisplayPrms which will finally call below function and
    HDMI clock is chosen.

    displayCtrlLink_drv.c: DisplayCtrlLink_configureVideoPllAndClkSrcForLCD
    /**************************************************************
    case SYSTEM_DCTRL_DSS_VENC_LCD2: (/* we are using LCD2 */)
    vencClkCfg.outputVenc = BSP_PLATFORM_VENC_LCD2;
    //vencClkCfg.vencClkSrc = BSP_PLATFORM_CLKSRC_DPLL_VIDEO1_CLKOUT3;
    vencClkCfg.vencClkSrc = BSP_PLATFORM_CLKSRC_DPLL_HDMI;
    break;
    **************************************************************/

    --------------------------------------------------------------------------------
    Flag: dssDispcMflagParam.globalMflagCtrl
    --------------------------------------------------------------------------------
    Previous value was 2, this changes was suggested by TI to set as 1.
    links_fw/src/rtos/links_ipu/display_ctrl/displayCtrlLink_drv.c:188: dssDispcMflagParam.globalMflagCtrl = 1;


    I will try to check by reverting the value to 2, would fix the issue. But here one difficulty is that
    getting the test vehicles and reproducing the issue would take time. If we could test couple of scenarios together, then would help save time and resources.

    Best Regards,
    RK

  • Flickering is seen after a short while HMI comes up. This is also means that by this time all M4 init sequence would have been completed long back. 

    Timeline wise: After bootup we see flicker after  > 15/17 seconds. 

    M4 init will be completed much before that ( < 2 seconds)

  • Hi Raghu,

    But do you see any underflow/sync lost when you see flicker? If not, it might not be coming from the video pipeline. 

    Regards,

    Brijesh

  • NO, as per our previous test, we dont see Sync loss

  • Have you tried different display device? 

  • Yes, below is replaced and verified but there is no improvement. 

    Display cable,

    display,

    HU. 

  • Do you mean the shakiness in the image at around 18 secont?

    Regards,

    Brijesh 

  • In the video file  which is shared offline. we could see flicker in time slot between 17- 19 seconds

  • Hi Raghu,

    Can you just send one fixed image to the display and see if there is any jumping in the image? This is just to see if this is coming from hdmi display or somewhere else in the chain?

    or can you run some standalone example and see if there is any corruption in the output image?

    Regards,

    Brijesh

  • Hi Brijesh, 

    As shared in offline screen shot,  can you please confirm whether testing with that screen are inline with your above test case ? 

    Best Regards,

    Raghu K

  • Hi Raghu,

    Can you stop switching the frames during this flicker? Essentially, just display static image for few seconds to see if this issue is coming from the HDMI or input to the display? 

    Regards,

    Brijesh

  • Hello Brijesh, 

    We have given for testing. it might take a short while to provide you feedback also adding reply so that  link is active. 

    Best Regards,

    Raghu Kadari

  • HI Brijesh, 

    with Static Image we are able to see Flicker as shared in video offline. 

    BR,

    RK

  • Hi Raghu,

    Does this issue come always or comes in specific condition? I think you had some early display usecase, So is this issue come during early display only or even in normal running usecase? 

    Can you compare display settings between working and non-working case, mainly HDMI settings? Also can you check clock source in both the cases? Is it same? Can you please check in register and make sure they are same? 

    Regards,

    Brijesh