From: Takashi Iwai <tiwai@suse.de>
Date: Mon, 15 Jun 2009 10:31:38 +0000 (+0200)
Subject: ALSA: intel8x0 - Fix PCM position craziness
X-Git-Tag: v2.6.31-rc1~308^2~1^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f708eb1d71dc8ffb184da9f0bc53461c6dc10653;p=pandora-kernel.git

ALSA: intel8x0 - Fix PCM position craziness

The PCM pointer callback sometimes returns invalid positions and this
screws up the hw_ptr updater in PCM core.  Especially since now the
jiffies check is optional with xrun_debug, the invalid position is
handled as is, and causes serious sound skips, etc.

This patch simplifies the position-fix strategy in intel8x0 to be more
robust:
- just falls back to the last position if bogus position is detected
- another sanity check for the backward move of the position due to
  a race of register update and the base-index update

This patch is applicable also for 2.6.30.

Tested-by: David Miller <davem@davemloft.net>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---

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