ALSA: hda - Update documentation
Update documentation regarding codec probing; the new probe_only option
and the new probe_mask usage.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt
index 841a936..012afd7 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -757,6 +757,9 @@
model - force the model name
position_fix - Fix DMA pointer (0 = auto, 1 = use LPIB, 2 = POSBUF)
probe_mask - Bitmask to probe codecs (default = -1, meaning all slots)
+ When the bit 8 (0x100) is set, the lower 8 bits are used
+ as the "fixed" codec slots; i.e. the driver probes the
+ slots regardless what hardware reports back
probe_only - Only probing and no codec initialization (default=off);
Useful to check the initial codec status for debugging
bdl_pos_adj - Specifies the DMA IRQ timing delay in samples.
diff --git a/Documentation/sound/alsa/HD-Audio.txt b/Documentation/sound/alsa/HD-Audio.txt
index 8d68fff..99f7fbb 100644
--- a/Documentation/sound/alsa/HD-Audio.txt
+++ b/Documentation/sound/alsa/HD-Audio.txt
@@ -109,6 +109,13 @@
Since 2.6.29 kernel, the driver has a more robust probing method, so
this error might happen rarely, though.
+On a machine with a broken BIOS, sometimes you need to force the
+driver to probe the codec slots the hardware doesn't report for use.
+In such a case, turn the bit 8 (0x100) of `probe_mask` option on.
+Then the rest 8 bits are passed as the codec slots to probe
+unconditionally. For example, `probe_mask=0x103` will force to probe
+the codec slots 0 and 1 no matter what the hardware reports.
+
Interrupt Handling
~~~~~~~~~~~~~~~~~~
@@ -461,6 +468,16 @@
There are some other useful options. See `--help` option output for
details.
+When a probe error occurs or when the driver obviously assigns a
+mismatched model, it'd be helpful to load the driver with
+`probe_only=1` option (at best after the cold reboot) and run
+alsa-info at this state. With this option, the driver won't configure
+the mixer and PCM but just tries to probe the codec slot. After
+probing, the proc file is available, so you can get the raw codec
+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.
+
hda-verb
~~~~~~~~