• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 98 subscribers
  • Views 328 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

AM335x 3.12 Kernel USB DMA problems

Richard Ziemerink
Prodigy 20 points

Hello,


We have a custom am335x board.  When running the USB ports with DMA enabled using the SDK7 3.12 linux kernel I can see that zero length packets coming in on a bulk transfer are incorrectly passed through as 1 byte values with a value of 0x00.  If I switch off the DMA (use PIO only) then the invalid bytes (or rather unexpected bytes) are not seen anymore.

I am pretty sure that this problem can be solved by filtering the packets based on the Zero-length packet indicator (bit 19 of the Packet descriptor Word 2).  Does anybody perhaps know if there is already a patch available to fix this problem before I start to dig deeper into the code?

Thanks,

Richard.