[PATCH] usb: mtu3: fix the failure of qmu stop

[AngeloGioacchino Del Regno]

Il 19/01/23 04:33, Chunfeng Yun ha scritto:
> This happens when do stress test of uvc stream on/off which will
> enable/disable endpoints. uvc has four tx requests, and may disable
> endpoint between queue tx requests as following:
>      enable ep --> start qmu
>      queue tx request0
>      queue tx request1
>      queue tx request2 --> resume qmu
>      disable ep --> stop qmu may fail [1]
>      queue tx request3 --> will resume qmu, may cause qmu can't work
>                            when enable ep next time [2]
> 
> [1]: when the tx fifo has some data to transmit, and
>      try to stop qmu (stop ep) meanwhile resume qmu (queue tx request),
>      it may cause stop qmu timeout, then can be fixed by flushing fifo
>      when stop qmu.
> [2]: it resumes qmu again, shall stop qmu again.
> 
> Signed-off-by: Chunfeng Yun <chunfeng.yun at mediatek.com>
> Reported-by: Min Guo <min.guo at mediatek.com>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno at collabora.com>