[alsa-devel] bug: reconfig broken on kernel 4.5

[Takashi Iwai]

On Mon, 09 May 2016 16:11:46 +0200,
Takashi Iwai wrote:
> 
> On Mon, 09 May 2016 10:22:49 +0200,
> Jochen Henneberg wrote:
> > 
> > Hi,
> > 
> > it looks as if 'reconfig' feature is broken since the sysfs attributes
> > have been moved to device attributes. In hda_sysfs.c:reconfig_codec()
> > the device is cleared with snd_hda_codec_reset() which calls
> > snd_hdac_device_unregister() which removes the sysfs entries (including
> > the currently in-use 'reconfig'), the re-registration fails afterwards
> > in snd_hda_codec_build_controls().
> > I am not sure when things got broken, but snd_hda_codec_reset()
> > called from reconfig_codec() unregisters the device and removes the
> > sysfs entries where in the past it only stripped all configurations
> > (pcms, controls ...) from the device.
> 
> Hrm, OK, something got broken indeed there.  I'll check it later.

Actually it's not about the sysfs, but rather the superfluous calls of
snd_hda_codec_build_controls() & co.  The fix patch is below.


Takashi

-- 8< --
From: Takashi Iwai <tiwai at suse.de>
Subject: [PATCH] ALSA: hda - Fix broken reconfig

The HD-audio reconfig function got broken in the recent kernels,
typically resulting in a failure like:
  snd_hda_intel 0000:00:1b.0: control 3:0:0:Playback Channel Map:0 is already present

This is because of the code restructuring to move the PCM and control
instantiation into the codec drive probe, by the commit [bcd96557bd0a:
ALSA: hda - Build PCMs and controls at codec driver probe].  Although
the commit above removed the calls of snd_hda_codec_build_pcms() and
*_build_controls() at the controller driver probe, the similar calls
in the reconfig were still left forgotten.  This caused the
conflicting and duplicated PCMs and controls.

The fix is trivial: just remove these superfluous calls from
reconfig_codec().

Fixes: bcd96557bd0a ('ALSA: hda - Build PCMs and controls at codec driver probe')
Reported-by: Jochen Henneberg <jh at henneberg-systemdesign.com>
Cc: <stable at vger.kernel.org> # v4.1+
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 sound/pci/hda/hda_sysfs.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/sound/pci/hda/hda_sysfs.c b/sound/pci/hda/hda_sysfs.c
index 64e0d1d81ca5..9739fce9e032 100644
--- a/sound/pci/hda/hda_sysfs.c
+++ b/sound/pci/hda/hda_sysfs.c
@@ -141,14 +141,6 @@ static int reconfig_codec(struct hda_codec *codec)
 	err = snd_hda_codec_configure(codec);
 	if (err < 0)
 		goto error;
-	/* rebuild PCMs */
-	err = snd_hda_codec_build_pcms(codec);
-	if (err < 0)
-		goto error;
-	/* rebuild mixers */
-	err = snd_hda_codec_build_controls(codec);
-	if (err < 0)
-		goto error;
 	err = snd_card_register(codec->card);
  error:
 	snd_hda_power_down(codec);
-- 
2.8.2