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@oikw.org 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@sakamocchi.jp Tested-by: Takashi Sakamoto o-takashi@sakamocchi.jp

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