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| author | Denis V. Lunev <den@openvz.org> | 2011-11-07 20:33:25 +0400 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2011-11-08 10:51:21 +0400 |
| commit | 5a9a51799b23142d2fc3ef94894d3b5ac00d05a5 (patch) | |
| tree | 44cb622d21314688a2b107fddba720e2136fc523 /sound/pci/intel8x0.c | |
| parent | 1ea6b8f48918282bdca0b32a34095504ee65bab5 (diff) | |
| download | linux-5a9a51799b23142d2fc3ef94894d3b5ac00d05a5.tar.xz | |
ALSA: intel8x0: Improve comments for VM optimization
The recently merged 228cf79376f1 looks a bit hackish while it is not.
The change was quite simple. In a virtualized environment the
patch unhacks old kludge introduced for old broken AC97 hardware.
This patch adds proper comment to "unkludge" code.
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Konstantin Ozerkov <kozerkov@parallels.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/pci/intel8x0.c')
| -rw-r--r-- | sound/pci/intel8x0.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/sound/pci/intel8x0.c b/sound/pci/intel8x0.c index 29e312597f20..c3b9bd0e188e 100644 --- a/sound/pci/intel8x0.c +++ b/sound/pci/intel8x0.c @@ -1077,6 +1077,13 @@ static snd_pcm_uframes_t snd_intel8x0_pcm_pointer(struct snd_pcm_substream *subs } if (civ != igetbyte(chip, ichdev->reg_offset + ICH_REG_OFF_CIV)) continue; + + /* IO read operation is very expensive inside virtual machine + * as it is emulated. The probability that subsequent PICB read + * will return different result is high enough to loop till + * timeout here. + * Same CIV is strict enough condition to be sure that PICB + * is valid inside VM on emulated card. */ if (chip->inside_vm) break; if (ptr1 == igetword(chip, ichdev->reg_offset + ichdev->roff_picb)) |