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ALSA: hda - Update document about MSI and interrupts

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Signed-off-by: Takashi Iwai <tiwai@suse.de>
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Takashi Iwai 2010-04-01 18:08:29 +02:00
parent b8e80cf386
commit 91cb17314e
1 changed files with 12 additions and 4 deletions
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Documentation/sound/alsa/HD-Audio.txt
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@ -119,10 +119,18 @@ the codec slots 0 and 1 no matter what the hardware reports.
Interrupt Handling
~~~~~~~~~~~~~~~~~~
In rare but some cases, the interrupt isn't properly handled as
default. You would notice this by the DMA transfer error reported by
ALSA PCM core, for example. Using MSI might help in such a case.
Pass `enable_msi=1` option for enabling MSI.
HD-audio driver uses MSI as default (if available) since 2.6.33
kernel as MSI works better on some machines, and in general, it's
better for performance. However, Nvidia controllers showed bad
regressions with MSI (especially in a combination with AMD chipset),
thus we disabled MSI for them.
There seem also still other devices that don't work with MSI. If you
see a regression wrt the sound quality (stuttering, etc) or a lock-up
in the recent kernel, try to pass `enable_msi=0` option to disable
MSI. If it works, you can add the known bad device to the blacklist
defined in hda_intel.c. In such a case, please report and give the
patch back to the upstream developer.
HD-AUDIO CODEC