[alsa-devel] [PATCH] ALSA: HDA: Use LPIB position fix for Macbook Pro 7, 1
tiwai at suse.de
Fri Jan 13 10:01:05 CET 2012
At Fri, 13 Jan 2012 09:55:56 +0100,
David Henningsson wrote:
> On 2012-01-13 09:50, Takashi Iwai wrote:
> > At Thu, 12 Jan 2012 16:31:14 +0100,
> > David Henningsson wrote:
> >> Several users have reported "choppy" audio under the 3.2 kernel,
> >> and that changing position_fix to 1 has resolved their problem.
> >> The chip is an nVidia Corporation MCP89 High Definition Audio,
> >> [10de:0d94] (rev a2).
> >> Cc: stable at kernel.org (v3.2+)
> >> BugLink: https://bugs.launchpad.net/bugs/909419
> >> Signed-off-by: David Henningsson<david.henningsson at canonical.com>
> > Applied now. Thanks.
> Just a thought...this was reported as working better under the previous
> Ubuntu release, which run kernel 3.0 (and not too many changes in
> PulseAudio), i e, a regression. While I haven't done any serious kernel
> bisection of this, I know you've being doing some work with the
> snoop/non-snoop stuff lately, which I haven't followed closely. Do you
> think this can be related to why we're seeing broken position values
> when we're using the DMA position buffer map on some machines?
Honestly I have no idea. The possibility can't be excluded, though,
since Windows seems using the non-cached pages as default.
The position-buffer is used primarily just because this was more
robust on old hardware. OTOH, LPIB seems more robust on modern chips,
so we may think of switching to LPIB, too.
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