Re: [PATCH v2] usb: xhci: Issue stop EP command only when the EP state is running

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On 16.06.2017 11:58, Shyam Sundar S K wrote:


On 6/9/2017 4:15 PM, Mathias Nyman wrote:
I think it's valid to check if the endpoint is already stopped from the endpoint context, and not
queue a stop endpoint command for a already stopped endpoint. Especially as your hardware can't handle it.
That code makes sense.


Thank you Mathias for the very detailed email :-) We spoke with our HW folks and they said that they are aware of
the WA limitations and scenarios it cannot cover. Unfortunately, there is no way to avoid the race condition and
we have to live with it.

So, it is possible to take the v2 of this patch ? or is it better to add a quirk for this specific revision of AMD HW which
cannot handle the scenario. Please advise.


Idea of patch v2 looks good, no need for quirk.
Patch still needs some cleaning up before it can be accepted.
Run scripts/checkpatch.pl on the patch fix those issues.

Would be a good idea to mention that the race issue is still possible in the commit message

Maybe some comment in the code could be added as well, like:
/* Check endpoint is running before stopping it, AMD SNPS 3.1 xHC may misbehave otherwise */

-Mathias
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