Use 31 bit DMA mask for Audigy

PATCH Applied Lee Revell 2 participants 2 messages Oct 25, 2005 Sound

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Lee Revell

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2005-10-25 04:08 UTC #0 lore raw

PATCH 1/1 Use 31 bit DMA mask for Audigy

I think this should go in 1.0.10 final. It seems to "fix" ALSA bug #1276.

It appears that either the Audigy DMA engine or the Linux kernel cannot handle 32 bit DMA with this device. Problem manifests as noise when using more than 2GB of RAM, possibly only on 64 bit machines.

The OSS driver actually uses a 29 bit DMA mask for both devices, this seems like overkill for now.

Signed-off-by Lee Revell <[email protected]>

sound/emu10k1.h renamed from sound/emu10k1.h-orig +2 -1

@@ -48,7 +48,8 @@
 
 /* FIXME? - according to the OSS driver the EMU10K1 needs a 29 bit DMA mask */
 #define EMU10K1_DMA_MASK	0x7fffffffUL	/* 31bit */
-#define AUDIGY_DMA_MASK		0xffffffffUL	/* 32bit */
+#define AUDIGY_DMA_MASK		0x7fffffffUL	/* 31bit FIXME - 32 should work? */
+						/* See ALSA bug #1276 - rlrevell */
 
 #define TMEMSIZE        256*1024
 #define TMEMSIZEREG     4

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Takashi Iwai

Applied

2005-10-25 10:28 UTC #1 lore raw

At Tue, 25 Oct 2005 00:08:16 -0400,

Quoted 7 lines · Lee Revell

I think this should go in 1.0.10 final. It seems to "fix" ALSA bug #1276.
It appears that either the Audigy DMA engine or the Linux kernel cannot handle 32 bit DMA with this device. Problem manifests as noise when using more than 2GB of RAM, possibly only on 64 bit machines.

Yes, ZONE_KERNEL won't be over 2GB usually on 32bit.

Quoted 4 lines

The OSS driver actually uses a 29 bit DMA mask for both devices, this seems like overkill for now.
Signed-off-by Lee Revell <[email protected]>

Thanks, applied to CVS.

Takashi