ALSA: Add debug module option

Add debug module option to snd core.
This controls the debug print level.  When CONFIG_SND_DEBUG_VERBOSE
is set, you can suppress the debug messages by giving or changing this
parameter to a lower value.  debug=0 means no debug messsages.
As default, it's set to the verbose level 2.

Since this option can be changed dynamically via sysfs file, you can
suppress the verbose debug messages on the fly, which wasn't possible
before.

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

1 files changed, 6 insertions, 0 deletions

diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt
index 4252697a95d..8e5b3488b37 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -60,6 +60,12 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
     slots       - Reserve the slot index for the given driver.
                   This option takes multiple strings.           
                   See "Module Autoloading Support" section for details.
+    debug       - Specifies the debug message level
+                  (0 = disable debug prints, 1 = normal debug messages,
+                   2 = verbose debug messages)
+                  This option appears only when CONFIG_SND_DEBUG=y.
+                  This option can be dynamically changed via sysfs
+                  /sys/modules/snd/parameters/debug file.
   
   Module snd-pcm-oss
   ------------------