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ALSA: dummy: Report a change when one capture switch channel moves

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The snd_dummy_capsrc_put() builds its change flag with &&, so it reports
a change only when both channels move at once.  Writing a single channel
stores the new value and returns 0, the control core then sends no
SNDRV_CTL_EVENT_MASK_VALUE, and a second reader keeps showing the old
setting until it polls again.

The volume put a few lines above compares the same pair of channels with
||.

The mixer selftest already reports this.  With snd-dummy loaded it fails
event_missing on all five capture switches:

  # CD Capture Switch.1 orig 0 read 1, is_volatile 0
  not ok 13 event_missing.Dummy.9

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Assisted-by: Claude:claude-opus-5
Signed-off-by: HyeongJun An <sammiee5311@gmail.com>
Link: https://patch.msgid.link/20260901153921.3971-1-sammiee5311@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
HyeongJun An 2026-09-02 00:39:21 +09:00 committed by Takashi Iwai
parent c53f5bfc37
commit 83162eeaf7
1 changed files with 1 additions and 1 deletions
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2
sound/drivers/dummy.c
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@ -808,7 +808,7 @@ static int snd_dummy_capsrc_put(struct snd_kcontrol *kcontrol, struct snd_ctl_el
left = ucontrol->value.integer.value[0] & 1;
right = ucontrol->value.integer.value[1] & 1;
guard(spinlock_irq)(&dummy->mixer_lock);
change = dummy->capture_source[addr][0] != left &&
change = dummy->capture_source[addr][0] != left ||
dummy->capture_source[addr][1] != right;
dummy->capture_source[addr][0] = left;
dummy->capture_source[addr][1] = right;