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ALSA: intel8x0: Improve comments for VM optimization

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The recently merged 228cf79376 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>
This commit is contained in:
Denis V. Lunev
2011-11-07 20:33:25 +04:00
committed by Takashi Iwai
parent 1ea6b8f489
commit 5a9a51799b
1 changed files with 7 additions and 0 deletions
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7
sound/pci/intel8x0.c
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@@ -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)) if (civ != igetbyte(chip, ichdev->reg_offset + ICH_REG_OFF_CIV))
continue; 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) if (chip->inside_vm)
break; break;
if (ptr1 == igetword(chip, ichdev->reg_offset + ichdev->roff_picb)) if (ptr1 == igetword(chip, ichdev->reg_offset + ichdev->roff_picb))