ALSA: emu10k1 - delay the PCM interrupts (add pcm_irq_delay parameter)

With some hardware combinations, the PCM interrupts are acknowledged
before the period boundary from the emu10k1 chip. The midlevel PCM code
gets confused and the playback stream is interrupted.

It seems that the interrupt processing shift by 2 samples is enough
to fix this issue. This default value does not harm other,
non-affected hardware.

More information: Kernel bugzilla bug#16300

[A copmile warning fixed by tiwai]

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 4 insertions, 0 deletions

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index a3b2a6479246..134fc6c2e08d 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -978,6 +978,10 @@ static int snd_pcm_do_pause(struct snd_pcm_substream *substream, int push)
 {
         if (substream->runtime->trigger_master != substream)
                 return 0;
+        /* some drivers might use hw_ptr to recover from the pause -
+           update the hw_ptr now */
+        if (push)
+                snd_pcm_update_hw_ptr(substream);
         /* The jiffies check in snd_pcm_update_hw_ptr*() is done by
          * a delta betwen the current jiffies, this gives a large enough
          * delta, effectively to skip the check once.