From 91cb17314e74d0e5ab572b4b84b9398c61b71abb Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Thu, 1 Apr 2010 18:08:29 +0200 Subject: ALSA: hda - Update document about MSI and interrupts Signed-off-by: Takashi Iwai --- Documentation/sound/alsa/HD-Audio.txt | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) (limited to 'Documentation/sound/alsa') diff --git a/Documentation/sound/alsa/HD-Audio.txt b/Documentation/sound/alsa/HD-Audio.txt index f4dd3bf99d1..98d14cb8a85 100644 --- a/Documentation/sound/alsa/HD-Audio.txt +++ b/Documentation/sound/alsa/HD-Audio.txt @@ -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 -- cgit v1.2.3-70-g09d2