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, 3 insertions, 1 deletions

diff --git a/sound/pci/emu10k1/memory.c b/sound/pci/emu10k1/memory.c
index ffb1ddb8dc28..957a311514c8 100644
--- a/sound/pci/emu10k1/memory.c
+++ b/sound/pci/emu10k1/memory.c
@@ -310,8 +310,10 @@ snd_emu10k1_alloc_pages(struct snd_emu10k1 *emu, struct snd_pcm_substream *subst
         if (snd_BUG_ON(!hdr))
                 return NULL;
 
+        idx = runtime->period_size >= runtime->buffer_size ?
+                                        (emu->delay_pcm_irq * 2) : 0;
         mutex_lock(&hdr->block_mutex);
-        blk = search_empty(emu, runtime->dma_bytes);
+        blk = search_empty(emu, runtime->dma_bytes + idx);
         if (blk == NULL) {
                 mutex_unlock(&hdr->block_mutex);
                 return NULL;