The HD-audio component consists of two parts: the controller chip and
the codec chips on the HD-audio bus. Linux provides a single driver
for all controllers, snd-hda-intel. Although the driver name contains
-a word of a well-known harware vendor, it's not specific to it but for
+a word of a well-known hardware vendor, it's not specific to it but for
all controller chips by other companies. Since the HD-audio
controllers are supposed to be compatible, the single snd-hda-driver
should work in most cases. But, not surprisingly, there are known
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
table until any matching entry is found. If you have a new machine,
you may see a message like below:
------------------------------------------------------------------------
+ hda_codec: ALC880: BIOS auto-probing.
+------------------------------------------------------------------------
+Meanwhile, in the earlier versions, you would see a message like:
+------------------------------------------------------------------------
hda_codec: Unknown model for ALC880, trying auto-probe from BIOS...
------------------------------------------------------------------------
Even if you see such a message, DON'T PANIC. Take a deep breath and
parser is much better than the generic parser (as now). Thus this
option is more about the debugging purpose.
-
Speaker and Headphone Output
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
One of the most frequent (and obvious) bugs with HD-audio is the
codec. This can work basically like the reconfiguration via sysfs in
the above, but it does it before the first codec configuration.
-The patch file looks like below:
+A patch file is a plain text file which looks like below:
------------------------------------------------------------------------
[codec]
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
+`patch=hda-init.fw`, the file /lib/firmware/hda-init-fw must be
+present.
+
+The patch module option is specific to each card instance, and you
+need to give one file name for each instance, separated by commas.
+For example, if you have two cards, one for an on-board analog and one
+for an HDMI video board, you may pass patch option like below:
+------------------------------------------------------------------------
+ options snd-hda-intel patch=on-board-patch,hdmi-patch
+------------------------------------------------------------------------
+
Power-Saving
~~~~~~~~~~~~
information before modified by the driver. Of course, the driver
isn't usable with `probe_only=1`. But you can continue the
configuration via hwdep sysfs file if hda-reconfig option is enabled.
+Using `probe_only` mask 2 skips the reset of HDA codecs (use
+`probe_only=3` as module option). The hwdep interface can be used
+to determine the BIOS codec initialization.
hda-verb
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
~~~~~~~~~~
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff