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Posted to commits@nuttx.apache.org by GitBox <gi...@apache.org> on 2020/08/22 13:38:42 UTC

[GitHub] [incubator-nuttx] johannes-nivus opened a new pull request #1624: Kinetis USBHSHOST improvement.

johannes-nivus opened a new pull request #1624:
URL: https://github.com/apache/incubator-nuttx/pull/1624


   Avoid race conditions during freeing of queue head structures by using Async Advance Doorbell.
   
   ## Summary
   During rewrite of FTDI FT232 driver (which will be a seperate PR), I realized that the EHCI host controller sometimes suddenly stops (RUN/STOP 0 HALTED 1).
   I tracked that down to interleaved in and out transfers which were causing race conditions between the host controller and the driver during QH unlink/reuse.
   EHCI Spec (4.8.2 Removing Queue Heads from Asynchronous Schedule) proposes the use of the Async Advance Doorbell mechanism to overcome that issue.
   ## Impact
   The unlinked QH are tagged and the Async Advance Doorbell process is started. When the corresponding interrupt occurs the QH are put on the free list.
   ## Testing
   Freedom K28 board, with modified FT2332R driver with a small stresstest application.
   
   Please ignore "error: Mixed case identifier found" complaints, they are related to a header file.
   


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[GitHub] [incubator-nuttx] Ouss4 merged pull request #1624: Kinetis USBHSHOST improvement.

Posted by GitBox <gi...@apache.org>.
Ouss4 merged pull request #1624:
URL: https://github.com/apache/incubator-nuttx/pull/1624


   


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[GitHub] [incubator-nuttx] Ouss4 commented on pull request #1624: Kinetis USBHSHOST improvement.

Posted by GitBox <gi...@apache.org>.
Ouss4 commented on pull request #1624:
URL: https://github.com/apache/incubator-nuttx/pull/1624#issuecomment-685094410


   Thanks @johannes-nivus.  Let's keep #1625 open for a reference to anyone coming across the same issue.


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