ALSA: hda - force use of SSYNC bits
SSYNC bits are typically used to start multiple
streams synchronously. It makes sense to use them
for a single stream for a more predictable startup
sequence. The transfers only start once the DMA and
FIFOs are ready. This results in a better correlation
between timestamps and number of samples played.
Credits to Kar Leong Wang for suggesting this
improvement.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
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 207d0a2..f4070a4 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -1986,14 +1986,14 @@
}
spin_lock(&chip->reg_lock);
- if (nsync > 1) {
- /* first, set SYNC bits of corresponding streams */
- if (chip->driver_caps & AZX_DCAPS_OLD_SSYNC)
- azx_writel(chip, OLD_SSYNC,
- azx_readl(chip, OLD_SSYNC) | sbits);
- else
- azx_writel(chip, SSYNC, azx_readl(chip, SSYNC) | sbits);
- }
+
+ /* first, set SYNC bits of corresponding streams */
+ if (chip->driver_caps & AZX_DCAPS_OLD_SSYNC)
+ azx_writel(chip, OLD_SSYNC,
+ azx_readl(chip, OLD_SSYNC) | sbits);
+ else
+ azx_writel(chip, SSYNC, azx_readl(chip, SSYNC) | sbits);
+
snd_pcm_group_for_each_entry(s, substream) {
if (s->pcm->card != substream->pcm->card)
continue;
@@ -2011,8 +2011,6 @@
}
spin_unlock(&chip->reg_lock);
if (start) {
- if (nsync == 1)
- return 0;
/* wait until all FIFOs get ready */
for (timeout = 5000; timeout; timeout--) {
nwait = 0;
@@ -2045,16 +2043,14 @@
cpu_relax();
}
}
- if (nsync > 1) {
- spin_lock(&chip->reg_lock);
- /* reset SYNC bits */
- if (chip->driver_caps & AZX_DCAPS_OLD_SSYNC)
- azx_writel(chip, OLD_SSYNC,
- azx_readl(chip, OLD_SSYNC) & ~sbits);
- else
- azx_writel(chip, SSYNC, azx_readl(chip, SSYNC) & ~sbits);
- spin_unlock(&chip->reg_lock);
- }
+ spin_lock(&chip->reg_lock);
+ /* reset SYNC bits */
+ if (chip->driver_caps & AZX_DCAPS_OLD_SSYNC)
+ azx_writel(chip, OLD_SSYNC,
+ azx_readl(chip, OLD_SSYNC) & ~sbits);
+ else
+ azx_writel(chip, SSYNC, azx_readl(chip, SSYNC) & ~sbits);
+ spin_unlock(&chip->reg_lock);
return 0;
}