TUSB7340: Getting 20FPS @1280x720 YUYV4:2:2 for UVC camera(USb2.0)

Hi Sagar:

    TUSB7340 bandwidth is limited by PCIe Gen2 speed. Your laptop  may has PCIe gen 4 or 5.  Unfortunately, there is no solution to increase bandwidth with current  TUSB7340.

Best

Brian

Hi Brian,

PCIe speed in not an issue since we are using USB2.0 UVC camera only which is 480Mbps while PCIe Gen2 is 5gbps.

From Software front or driver front can be increase the BW. Since with other Vendor PCIe GEN2 to USB2.0 we are getting 22FPS. Le t me know if there is any room to increase the BW.

Thanks

Sagar

Hi Sagar:

  What is real data rate for  1280x 720 resolution in YUYV4:2:2 Format with 25 fps?

  Normally USB2 bandwidth is around 30-40 MB/s, which is 240-320 Mbps/s .

Regards

Brian

Hi Brian,

It is 276.48Mbps or 34.5MB/s. With other Vendor PCIe to USB bridge we are getting 22FPS while with Laptop using USB2.0 cable which have native USB interface we are getting 25FPS. It seems like TUSB7340 is sending more payload/protocol data which restricted the data rate .

Thanks

Sagar

Hi Sagar:

   I agree, TUSB7340  bandwidth is in low 30MB/s, it  may send  more payload  than other  PCIe to USB bridge.

Regards

Brian

Hi Brian,

Do you have any official data or any app notes regarding the USB2.0 bandwidth for TUSB7340.

Thanks

Sagar

Hi Sagar:

   We did have throughout data before, just can't find at this moment. I may need to re-take data when back to office sometime this week when snow weather is over.

Regards

Brian

I only got 19MB/s  for USB2 read for TUSB7340.

Best

Brian

Seems something is wrong in data, we are getting 30MB/s with USB2.0 Pendrive.

What test tool you used for test? I was using Crystaldiskmark .

Regards

brian

hdparm -t --direct /dev/sda

after connecting the pendrive we are using this command.

Thanks

Sagar

Is this Linux   command? It didn't work on Windows system.

But anyway,  30MB/s can not  support  25FPS.

Best

Brian

Yes it is Linux command.

I just want a throughput testing data from TI so that i can conclude with TUSB7340 is not suitable for our camera application. or is there any way to increase the through put via change in payload data / PCIe latency?
Thanks

Sagar

For USB2 UVC camera, it may require increasing software buffer size if using bulk transfer. Can you change it to Isochronous  mode?

also adjust power  states dynamically to reduce latency during idle period, freeing bandwidth for active streams.

in Linux, you can try disable autosuspend .

Best

Brian