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[v3,5/6] ALSA: chmap: Mark Channel Map controls as volatile

Message ID 20240616073454.16512-6-tiwai@suse.de
State Accepted
Commit 210e6a844112bd7e28a04faedac677918e1f3040
Headers show
Series ALSA: some driver fixes for control input validations | expand

Commit Message

Takashi Iwai June 16, 2024, 7:34 a.m. UTC 
The values returned from Playback Channel Map and Capture Channel Map
controls may vary dynamically depending on the corresponding PCM
stream.  Mark those as volatile to indicate the values are unstable
and not suitable for testing.

Note that we may change the driver to return -EINVAL, but this would
bring other side effects, such as "alsactl restore" would start
receiving unexpected errors.  So we still keep returning 0 for those
invalid inputs.

Reported-by: Paul Menzel <pmenzel@molgen.mpg.de>
Closes: https://lore.kernel.org/r/1d44be36-9bb9-4d82-8953-5ae2a4f09405@molgen.mpg.de
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/core/pcm_lib.c | 1 +
 1 file changed, 1 insertion(+)
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Patch

diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 6f73b3c2c205..071c67cbc479 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -2556,6 +2556,7 @@  int snd_pcm_add_chmap_ctls(struct snd_pcm *pcm, int stream,
 	struct snd_kcontrol_new knew = {
 		.iface = SNDRV_CTL_ELEM_IFACE_PCM,
 		.access = SNDRV_CTL_ELEM_ACCESS_READ |
+			SNDRV_CTL_ELEM_ACCESS_VOLATILE |
 			SNDRV_CTL_ELEM_ACCESS_TLV_READ |
 			SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK,
 		.info = pcm_chmap_ctl_info,