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AM335x SDK6 PSP04.06.00.11 --- USB driver and Zero Length Packet

Gunter Schmer
Genius 14202 points

Hi,

 

using the AM335x SDK 6.00 with PSP 04.06.00.11 we are running into a USB driver issue with Zero Length packet (ZLP). Here is the use

I have recently run into a problem when reading data from a USB bulk endpoint with libusb on the EVM. A change was made recently to the FX2 firmware on our USB probes that enabled zero length packets (ZLP)to be sent when a transfer ends on a multiple of the transfer size of 512 bytes. This fixed an issue we were seeing under Windows where during high throughput situations 2 frames would be combined because the 2nd frame came in right after the 1st frame with no pause between. While the ZLP change fixed things under Windows, it broke things under Linux on the EVM.

The protocol analyzer seems to show that the ZLP makes it across and gets ack'ed but somehow makes the driver fail.

What debug should be enabled to see more, I see a menuconfig debug in the musb driver.

Could this issue be similar to this one?

http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/p/281894/1080528.aspx#1080528

 

Please let us know what you think and whether we have seen this before.

 

Thanks,

--Gunter