[Regression drm-tip] Internal audio device missing

[Takashi Iwai]

On Thu, 26 Dec 2019 10:47:18 +0100,
Paul Menzel wrote:
> 
> Dear Linux folks,
> 
> 
> With
> 
>     $ git describe --tags drm-tip/drm-tip
>     v5.5-rc3-1481-ga20d8cd6901a
> 
> the internal audio device is not available, and just a dummy device.
> 
> Running `alsa-info.sh` [1], the messages below are shown with the
> problematic Linux kernel.
> 
>     alsactl: get_controls:567: snd_ctl_open error: Sound protocol is
> not compatible
>     cat: /tmp/alsa-info.ateDlDjrZX/alsactl.tmp: No such file or directory

That's an unexpected side-effect of the recent protocol version bump
in sound.git for-next branch.  It seems that we can't change the minor
version unless we really want to break something.

Below is the fix patch.  Please give it a try.


thanks,

Takashi

-- 8< --
From: Takashi Iwai <tiwai at suse.de>
Subject: [PATCH] ALSA: control: Fix incompatible protocol error

The recent change to bump the ALSA control API protocol version from
2.0.7 to 2.1.0 caused a regression on user-space; while the user-space
expects both the major and the minor versions to be identical with the
supported numbers, we changed the minor number from 0 to 1.

For recovering from the incompatibility, this patch changes the
protocol version again to 2.0.8, which is compatible, but yet higher
than the original number 2.0.7, indicating that the protocol change.

Fixes: bd3eb4e87eb3 ("ALSA: ctl: bump protocol version up to v2.1.0")
Reported-by: Paul Menzel <pmenzel at molgen.mpg.de>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 include/uapi/sound/asound.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
index e36dadaf84ba..30ebb2a42983 100644
--- a/include/uapi/sound/asound.h
+++ b/include/uapi/sound/asound.h
@@ -936,7 +936,7 @@ struct snd_timer_tread {
  *                                                                          *
  ****************************************************************************/
 
-#define SNDRV_CTL_VERSION		SNDRV_PROTOCOL_VERSION(2, 1, 0)
+#define SNDRV_CTL_VERSION		SNDRV_PROTOCOL_VERSION(2, 0, 8)
 
 struct snd_ctl_card_info {
 	int card;			/* card number */
-- 
2.16.4