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Diffstat (limited to 'Documentation/sound/alsa/HD-Audio.txt')
| -rw-r--r-- | Documentation/sound/alsa/HD-Audio.txt | 49 |
1 files changed, 43 insertions, 6 deletions
diff --git a/Documentation/sound/alsa/HD-Audio.txt b/Documentation/sound/alsa/HD-Audio.txt index 7b8a5f947d1..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 @@ -452,6 +460,33 @@ Similarly, the lines after `[verb]` are parsed as `init_verbs` sysfs entries, and the lines after `[hint]` are parsed as `hints` sysfs entries, respectively. +Another example to override the codec vendor id from 0x12345678 to +0xdeadbeef is like below: +------------------------------------------------------------------------ + [codec] + 0x12345678 0xabcd1234 2 + + [vendor_id] + 0xdeadbeef +------------------------------------------------------------------------ + +In the similar way, you can override the codec subsystem_id via +`[subsystem_id]`, the revision id via `[revision_id]` line. +Also, the codec chip name can be rewritten via `[chip_name]` line. +------------------------------------------------------------------------ + [codec] + 0x12345678 0xabcd1234 2 + + [subsystem_id] + 0xffff1111 + + [revision_id] + 0x10 + + [chip_name] + My-own NEWS-0002 +------------------------------------------------------------------------ + The hd-audio driver reads the file via request_firmware(). Thus, a patch file has to be located on the appropriate firmware path, typically, /lib/firmware. For example, when you pass the option @@ -624,11 +659,13 @@ hda-verb. The program gives you an easy-to-use GUI stuff for showing the widget information and adjusting the amp values, as well as the proc-compatible output. -The hda-analyzer is a part of alsa.git repository in -alsa-project.org: +The hda-analyzer: - http://git.alsa-project.org/?p=alsa.git;a=tree;f=hda-analyzer +is a part of alsa.git repository in alsa-project.org: + +- git://git.alsa-project.org/alsa.git Codecgraph ~~~~~~~~~~ |