ALSA: hda: option to enable arbitrary buffer/period sizes

Add new parameter to disable rounding of buffer/period sizes to
multiples of 128 bytes. This is more efficient in terms of memory
access but isn't required by the HDA spec and prevents users from
specifying exact period/buffer sizes. For example for 44.1kHz, a
period size set to 20ms will be rounded to 19.59ms.

Tested and enabled on Intel HDA controllers. Option is disabled by
default for other controllers.

Tested-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 5 insertions, 0 deletions

diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt
index 89757012c7ff..27126c469f70 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -886,6 +886,11 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
                 disable)
     power_save_controller - Reset HD-audio controller in power-saving mode
                 (default = on)
+    align_buffer_size - Force rounding of buffer/period sizes to multiples
+                      of 128 bytes. This is more efficient in terms of memory
+                      access but isn't required by the HDA spec and prevents
+                      users from specifying exact period/buffer sizes.
+                      (default = on)
 
     This module supports multiple cards and autoprobe.