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| author | Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> | 2012-09-21 18:39:05 -0500 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2012-09-22 09:28:10 +0200 |
| commit | 172d3b209622785ce7c4f4104319df06d9814b62 (patch) | |
| tree | 83584dcecb552bc87b3c628fcdfdc0d240370aed /sound | |
| parent | cf55e904516947597d75fd3844acc24891a95772 (diff) | |
| download | linux-stable-172d3b209622785ce7c4f4104319df06d9814b62.tar.gz linux-stable-172d3b209622785ce7c4f4104319df06d9814b62.tar.bz2 linux-stable-172d3b209622785ce7c4f4104319df06d9814b62.zip | |
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>
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/pci/hda/hda_intel.c | 36 |
1 files changed, 16 insertions, 20 deletions
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c index 207d0a20f317..f4070a4f39fd 100644 --- a/sound/pci/hda/hda_intel.c +++ b/sound/pci/hda/hda_intel.c @@ -1986,14 +1986,14 @@ static int azx_pcm_trigger(struct snd_pcm_substream *substream, int cmd) } 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 @@ static int azx_pcm_trigger(struct snd_pcm_substream *substream, int cmd) } 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 @@ static int azx_pcm_trigger(struct snd_pcm_substream *substream, int cmd) 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; } |