ALSA: hda - More description about patch module option

Signed-off-by: Takashi Iwai <tiwai@suse.de>

Documentation/sound/alsa/ALSA-Configuration.txt

@@ -749,6 +749,10 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
     bdl_pos_adj	- Specifies the DMA IRQ timing delay in samples.
 		Passing -1 will make the driver to choose the appropriate
 		value based on the controller chip.
+    patch	- Specifies the early "patch" files to modify the HD-audio
+    		setup before initializing the codecs.  This option is
+		available only when CONFIG_SND_HDA_PATCH_LOADER=y is set.
+		See HD-Audio.txt for details.
     
     [Single (global) options]
     single_cmd  - Use single immediate commands to communicate with

Documentation/sound/alsa/HD-Audio.txt

@@ -410,7 +410,7 @@ firmware file for modifying the HD-audio setup before initializing 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]
@@ -448,6 +448,20 @@ Similarly, the lines after `[verb]` are parsed as `init_verbs`
 sysfs entries, and the lines after `[hint]` are parsed as `hints`
 sysfs entries, respectively.
 
+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
 ~~~~~~~~~~~~