ALSA: hda - Add workaround for CMI8888 snoop behavior

CMI8888 shows the stuttering playback when the snooping is disabled
on the audio buffer.  Meanwhile, we've got reports that CORB/RIRB
doesn't work in the snooped mode.  So, as a compromise, disable the
snoop only for CORB/RIRB and enable the snoop for the stream buffers.

The resultant patch became a bit ugly, unfortunately, but we still can
live with it.

Reported-and-tested-by: Geoffrey McRae <geoff@spacevs.com>
Cc: <stable@vger.kernel.org> # 3.17+
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index cfcca4c..9ab1e63 100644 (file)
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -374,6 +374,8 @@ static void __mark_pages_wc(struct azx *chip, struct snd_dma_buffer *dmab, bool
 #ifdef CONFIG_SND_DMA_SGBUF
        if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_SG) {
                struct snd_sg_buf *sgbuf = dmab->private_data;
+               if (chip->driver_type == AZX_DRIVER_CMEDIA)
+                       return; /* deal with only CORB/RIRB buffers */
                if (on)
                        set_pages_array_wc(sgbuf->page_table, sgbuf->pages);
                else
@@ -1769,7 +1771,7 @@ static void pcm_mmap_prepare(struct snd_pcm_substream *substream,
 #ifdef CONFIG_X86
        struct azx_pcm *apcm = snd_pcm_substream_chip(substream);
        struct azx *chip = apcm->chip;
-       if (!azx_snoop(chip))
+       if (!azx_snoop(chip) && chip->driver_type != AZX_DRIVER_CMEDIA)
                area->vm_page_prot = pgprot_writecombine(area->vm_page_prot);
 #endif
 }