Re: [PATCH] ALSA: usb-audio: fix urb timeout with URB_ISO_ASAP flag

[Michael Wu]

On 11/22/2022 4:46 PM, Takashi Iwai wrote:
> On Tue, 22 Nov 2022 09:20:40 +0100,
> Michael Wu wrote:
> > When the loglevel is greater than 4, with a long messages printed on the
> > console while playing or recording audios, the usb controller may become
> > abnormal.
> > `usb 1-2: timeout: still 1 active urbs on EP #1`
> >
> > Fix it by configuring the transfer_flags URB_ISO_ASAP flag.
> >
> > Signed-off-by: Michael Wu <michael@xxxxxxxxxxxxxxxxx>
>
> Hrm, that's somewhat backward action to the change we've done years
> ago, commit c75c5ab575af7db707689cdbb5a5c458e9a034bb:
>
>      ALSA: USB: adjust for changed 3.8 USB API
>      
>      The recent changes in the USB API ("implement new semantics for
>      URB_ISO_ASAP") made the former meaning of the URB_ISO_ASAP flag the
>      default, and changed this flag to mean that URBs can be delayed.
>      This is not the behaviour wanted by any of the audio drivers because
>      it leads to discontinuous playback with very small period sizes.
>      Therefore, our URBs need to be submitted without this flag.
>
> I rather suspect that your problem is in the USB controller side.
>
>
> thanks,
>
> Takashi
Dear Takashi, thanks for the reminding. Let me check...

--
Regards,
Michael Wu