diff options
| author | Cezary Rojewski <cezary.rojewski@intel.com> | 2026-02-24 23:56:19 +0300 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2026-02-28 11:32:39 +0300 |
| commit | 84446536f63d471ab16b2faa25eeab1df21ace0a (patch) | |
| tree | 365d8b5ba9bff72a9eed854f8229a9fd863c85bb /include | |
| parent | d4d5633d8b19b0e745a7910aea49956b3b47900d (diff) | |
| download | linux-84446536f63d471ab16b2faa25eeab1df21ace0a.tar.xz | |
ALSA: control: Verify put() result when in debug mode
The put() operation is expected to return:
1) 0 on success if no changes were made
2) 1 on success if changes were made
3) error code otherwise
Currently 2) is usually ignored when writing control-operations. While
forcing compliance is not an option right now, make it easier for
developers to adhere to the expectations and notice problems by logging
them when CONFIG_SND_CTL_DEBUG is enabled.
Due to large size of struct snd_ctl_elem_value, 'value_buf' is provided
as a reusable buffer for kctl->put() verification. This prevents
exhausting the stack when verifying the operation.
>From user perspective, patch introduces a new trace/events category
'snd_ctl' containing a single 'snd_ctl_put' event type. Log sample:
amixer-1086 [003] ..... 8.035939: snd_ctl_put: success: expected=0, actual=0 for ctl numid=1, iface=MIXER, name='Master Playback Volume', index=0, device=0, subdevice=0, card=0
amixer-1087 [003] ..... 8.938721: snd_ctl_put: success: expected=1, actual=1 for ctl numid=1, iface=MIXER, name='Master Playback Volume', index=0, device=0, subdevice=0, card=0
amixer-1088 [003] ..... 9.631470: snd_ctl_put: success: expected=1, actual=1 for ctl numid=1, iface=MIXER, name='Master Playback Volume', index=0, device=0, subdevice=0, card=0
amixer-1089 [000] ..... 9.636786: snd_ctl_put: fail: expected=1, actual=0 for ctl numid=5, iface=MIXER, name='Loopback Mute', index=0, device=0, subdevice=0, card=0
Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20260224205619.584795-1-cezary.rojewski@intel.com
Diffstat (limited to 'include')
| -rw-r--r-- | include/sound/core.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/sound/core.h b/include/sound/core.h index 64327e971122..4093ec82a0a1 100644 --- a/include/sound/core.h +++ b/include/sound/core.h @@ -133,6 +133,9 @@ struct snd_card { #ifdef CONFIG_SND_DEBUG struct dentry *debugfs_root; /* debugfs root for card */ #endif +#ifdef CONFIG_SND_CTL_DEBUG + struct snd_ctl_elem_value *value_buf; /* buffer for kctl->put() verification */ +#endif #ifdef CONFIG_PM unsigned int power_state; /* power state */ |