[ALSA] Support all sample rate conversion capabilities of DXS channels

Documentation,VIA82xx driver
Add support for full sample rate conversion capabilities of DXS
channels present in VIA VT8233/5/7 controllers:

- any sample rate in the 8000 ... 48000 Hz range is supported even if
  the AC'97 codec supports only 48000 Hz output;

- different DXS channels can use different sample rates at the same
  time (the controller performs required sample rate conversion and
  mixing in hardware).

Signed-off-by: Sergey Vlasov <vsu@altlinux.ru>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 13 insertions, 8 deletions

diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt
index 71ef0498d5e0..c69581ca2a34 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -1211,16 +1211,18 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
   ------------------
 
     Module for AC'97 motherboards based on VIA 82C686A/686B, 8233,
-    8233A, 8233C, 8235 (south) bridge.
+    8233A, 8233C, 8235, 8237 (south) bridge.
 
     mpu_port    - 0x300,0x310,0x320,0x330, otherwise obtain BIOS setup
                   [VIA686A/686B only]
     joystick    - Enable joystick (default off) [VIA686A/686B only]
     ac97_clock  - AC'97 codec clock base (default 48000Hz)
     dxs_support - support DXS channels,
-                  0 = auto (defalut), 1 = enable, 2 = disable,
-                  3 = 48k only, 4 = no VRA
-                  [VIA8233/C,8235 only]
+                  0 = auto (default), 1 = enable, 2 = disable,
+                  3 = 48k only, 4 = no VRA, 5 = enable any sample
+                  rate and different sample rates on different
+                  channels
+                  [VIA8233/C, 8235, 8237 only]
     ac97_quirk  - AC'97 workaround for strange hardware
                   See the description of intel8x0 module for details.
 
@@ -1232,18 +1234,21 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
           default value 1.4.  Then the interrupt number will be
           assigned under 15. You might also upgrade your BIOS.
     
-    Note: VIA8233/5 (not VIA8233A) can support DXS (direct sound)
+    Note: VIA8233/5/7 (not VIA8233A) can support DXS (direct sound)
           channels as the first PCM.  On these channels, up to 4
-          streams can be played at the same time.
+          streams can be played at the same time, and the controller
+          can perform sample rate conversion with separate rates for
+          each channel.
           As default (dxs_support = 0), 48k fixed rate is chosen
           except for the known devices since the output is often
           noisy except for 48k on some mother boards due to the
           bug of BIOS.
-          Please try once dxs_support=1 and if it works on other
+          Please try once dxs_support=5 and if it works on other
           sample rates (e.g. 44.1kHz of mp3 playback), please let us
           know the PCI subsystem vendor/device id's (output of
           "lspci -nv").
-          If it doesn't work, try dxs_support=4.  If it still doesn't
+          If dxs_support=5 does not work, try dxs_support=1; if it
+          doesn't work too, try dxs_support=4.  If it still doesn't
           work and the default setting is ok, dxs_support=3 is the
           right choice.  If the default setting doesn't work at all,
           try dxs_support=2 to disable the DXS channels.