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Commit 5a9a51799b23142d2fc3ef94894d3b5ac00d05a5

Authored by Denis V. Lunev
Committed by Takashi Iwai
1 parent 1ea6b8f489
Exists in master and in 6 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

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>

Showing 1 changed file with 7 additions and 0 deletions Side-by-side Diff

sound/pci/intel8x0.c
Diff comments   View file @ 5a9a517
... ... @@ -1077,6 +1077,13 @@
1077 1077 }
1078 1078 if (civ != igetbyte(chip, ichdev->reg_offset + ICH_REG_OFF_CIV))
1079 1079 continue;
  1080 +
  1081 + /* IO read operation is very expensive inside virtual machine
  1082 + * as it is emulated. The probability that subsequent PICB read
  1083 + * will return different result is high enough to loop till
  1084 + * timeout here.
  1085 + * Same CIV is strict enough condition to be sure that PICB
  1086 + * is valid inside VM on emulated card. */
1080 1087 if (chip->inside_vm)
1081 1088 break;
1082 1089 if (ptr1 == igetword(chip, ichdev->reg_offset + ichdev->roff_picb))