ALSA: hda - Add position_fix=4 (COMBO) option

This patch adds a new position_fix option value, 4, as a combo mode
to use LPIB for playbacks and POSBUF for captures.  It's the way
recommended by Intel hardware guys.

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 936699e..9af64c5 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -860,7 +860,8 @@
 
     [Multiple options for each card instance]
     model	- force the model name
-    position_fix - Fix DMA pointer (0 = auto, 1 = use LPIB, 2 = POSBUF)
+    position_fix - Fix DMA pointer (0 = auto, 1 = use LPIB, 2 = POSBUF,
+    		   3 = VIACOMBO, 4 = COMBO)
     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
@@ -925,6 +926,11 @@
 	    (Usually SD_LPIB register is more accurate than the
 	    position buffer.)
 
+	    position_fix=3 is specific to VIA devices.  The position
+	    of the capture stream is checked from both LPIB and POSBUF
+	    values.  position_fix=4 is a combination mode, using LPIB
+	    for playback and POSBUF for capture.
+
     NB: If you get many "azx_get_response timeout" messages at
     loading, it's likely a problem of interrupts (e.g. ACPI irq
     routing).  Try to boot with options like "pci=noacpi".  Also, you