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, 1 insertions, 0 deletions

diff --git a/include/sound/emu10k1.h b/include/sound/emu10k1.h
index 6a664c3f7c1e..7dc97d12253c 100644
--- a/include/sound/emu10k1.h
+++ b/include/sound/emu10k1.h
@@ -1707,6 +1707,7 @@ struct snd_emu10k1 {
         unsigned int card_type;                 /* EMU10K1_CARD_* */
         unsigned int ecard_ctrl;                /* ecard control bits */
         unsigned long dma_mask;                 /* PCI DMA mask */
+        unsigned int delay_pcm_irq;             /* in samples */
         int max_cache_pages;                    /* max memory size / PAGE_SIZE */
         struct snd_dma_buffer silent_page;      /* silent page */
         struct snd_dma_buffer ptb_pages;        /* page table pages */