Hi,
On Jul 18 2016 01:16, Kazuki Oikawa wrote:
> snd_usb_{set_interface,ctl_msg}_quirk checks chip->usb_id to need
> calling a quirks code. But existed code path that not calling
> dev_set_drvdata in usb_audio_probe.
>
> Signed-off-by: Kazuki Oikawa <k@xxxxxxxx>
> Fixes: 79289e24194a ("ALSA: usb-audio: Refer to chip->usb_id for quirks and MIDI creation")
> ---
> sound/usb/card.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/sound/usb/card.c b/sound/usb/card.c
> index 3fc63583a537..2d493501b7f6 100644
> --- a/sound/usb/card.c
> +++ b/sound/usb/card.c
> @@ -552,7 +552,6 @@ static int usb_audio_probe(struct usb_interface *intf,
> goto __error;
> }
> chip = usb_chip[i];
> - dev_set_drvdata(&dev->dev, chip);
> atomic_inc(&chip->active); /* avoid autopm */
> break;
> }
> @@ -578,6 +577,7 @@ static int usb_audio_probe(struct usb_interface *intf,
> goto __error;
> }
> }
> + dev_set_drvdata(&dev->dev, chip);
>
> /*
> * For devices with more than one control interface, we assume the
Reviewed-by: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>
Tested-by: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>
Let me describe supplemental comments.
This bug affects all of USB devices which take USB subsystem to call an
implementation of struct usb_driver.probe() in snd-usb-audio
(=usb_audio_probe()) just one time. In this case, dev_set_drvdata() is
not called at first call of usb_audio_probe(), then dev_get_drvdata()
returns NULL.
As a result, some quirks are not handled. snd_usb_set_interface_quirk()
and snd_usb_set_interface_quirk() returns immediately without enough
operations. This brings regressions to some models.
As long as I asked to Mr.Oikawa in this morning, below models are affected.
* Playback Design
* TEAC
* Marantz
* Denon
* Zoom R16/24
I tested with EMU 0404 USB. This model has no quirks related to above
functions, but it brings just one call of usb_audio_probe(). Then,
without this patch, I can see dev_get_drvdata() always returns NULL
whole lifetime of usb device instance.
(But even with this patch, in a call of snd_usb_audio_free(),
dev_get_drvdata() returns NULL before a call of dev_set_devdata(NULL),
against my expectation. I don't know why...)
This patch should go for 4.8 merge window.
Regards
Takashi Sakamoto
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