Re: [PATCH 1/3] usb: dwc3: gadget: Properly handle failed kick_transfer

[Felipe Balbi <balbi@kernel.org>]

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Hi,

Thinh Nguyen <Thinh.Nguyen@synopsys.com> writes:
>> Thinh Nguyen <Thinh.Nguyen@synopsys.com> writes:
>>> If dwc3 fails to issue START_TRANSFER/UPDATE_TRANSFER command, then we
>>> should properly end an active transfer and give back all the started
>>> requests. However if it's for an isoc endpoint, the failure maybe due to
>>> bus-expiry status. In this case, don't give back the requests and wait
>>> for the next retry.
>>>
>>> Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver")
>>> Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
>> could you give some details regarding when does this happen?
>>
>
> So, here are the scenarios in which dwc3_send_gadget_ep_cmd() may return 
> a negative errno:
>
> * -EAGAIN: Isoc bus-expiry status
>     As you already know, this occurs when we try to schedule isoc too 
> late. If we're going to retry the request, don't unmap it.

right

> * -EINVAL: No resource due to issuing START_TRANSFER to an already 
> started endpoint
>     This happens generally because of SW programming error

Sounds like this should be fixed separately and, probably, we should add
a WARN() so we catch these situations. Have you reproduced this
particular case?

> * -ETIMEDOUT: Polling for CMDACT timed out
>     This should not happen unless the controller is dead or in some bad 
> state

Understood

-- 
balbi

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