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Degradation in USB performance

Subbarao PNV
Prodigy 60 points

Processor: OMAP 3530

BSP version: TI_EVM_3530 - 6.13.00 and TI_EVM_3530 - 6.14.00

Platform: EVM

We have developed a UVC (Bulk transfer) client driver with BSP version 6_13_00 and achieved the frame rate of 28. Now we shifted to the BSP version 6_14_00, with this version UVC frame rate has come down to 25. I have replaced the USB client drivers of version 14 BSP with version 13 BSP, but I didn’t find any significant change in the frame rate.

Can any body help on this, which component in the BSP can make this difference?

 Thanks,

Subbarao.

  • TI__Genius 9185 points

    Can you check if the file cache manager setting (this has nothing to do with the BSP) is different in your setup between the tests.

  • in reply to Jatin Jain
    TI__Genius 9185 points

    Could you also describe what the application is doing in more detail. You mentioned frame rate. Does this mean video decode and display is active in this application as well. That may give some clue if any of the related functionality could be affecting performance.

     

  • in reply to Jatin Jain
    Prodigy 60 points

    Hi Jatin,

    Thanks for your reply.

    We are not working with any type of video play back application on OMAP Evaluation platform.

    We have developed a UVC (using Bulk transfer type ) client driver and a camera is connected to the OMAP 3530 Rev D evaluation board. Our UVC client driver will access the camera interface to get the camera frames. 

    when the OMAP Evaluation board is conencted to the host PC with USB cable, OMAP will be detected as a Generic UVC device and we are running AmCap application on host PC to view the camera preview. Since the AmCap application is running on Host PC, we can observe the frame rate on host PC only not on OMAP device.

    As soon as the AmCap application launched on host PC, UVC client driver will get a notification from the host then it will start sending the camera frames to host PC.

    First we started the UVC client driver development with BSP version 13 and we achieved the frame rate of 28 on Host PC. Now we are using BSP version 14 and same UVC client driver but frame rate came down to 25. 

    In one of your reply, you mentioned to check the file cache manager settings. since there are no file related operation in driver, Can you explain how it can be a reason for frame rate reduction.

    Thanks,

    Subbarao.

     

  • in reply to Subbarao PNV
    TI__Genius 9185 points

    Subbarao,

    My reference to the file cache manager was related to CETK SD card tests where disabling caching helps significantly with read tests but degrades write tests (I'm not familiar with the USB bulk transfer and whether file cache manager plays a part in it or not). But if this flag did not change between your test setups then obviously something else is causing the problem.

    Can you also confirm if USB OTG HS mode setting (DisableHighSpeed) is same between your setups (by default HS mode was disabled in both BSP 6.13.00 and BSP 6.14.00 releases in platform.reg but not sure if you changed it). FYI. USB OTG HS mode is enabled by default in BSP 6.14.01 release.

    Any difference in ARM utilization between the 2 tests?

    Jatin

  • in reply to Jatin Jain
    TI__Genius 9185 points

    Subbarao,

    Were you able to find the root cause of the degradation? Thanks.

    Jatin