[PATCH] Use 31 bit DMA mask for Audigy

[PATCH] Use 31 bit DMA mask for Audigy

[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.

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

Signed-Off-By: Lee Revell <rlrevell@joe-job.com>

--- include/sound/emu10k1.h-orig	2005-10-11 12:31:42.000000000 -0400
+++ include/sound/emu10k1.h	2005-10-25 00:00:51.000000000 -0400
@@ -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




-------------------------------------------------------
This SF.Net email is sponsored by the JBoss Inc.
Get Certified Today * Register for a JBoss Training Course
Free Certification Exam for All Training Attendees Through End of 2005
Visit http://www.jboss.com/services/certification for more information

Re: [PATCH] Use 31 bit DMA mask for Audigy

[Takashi Iwai]

At Tue, 25 Oct 2005 00:08:16 -0400,
Lee Revell wrote:
> 
> 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.

> The OSS driver actually uses a 29 bit DMA mask for both devices, this
> seems like overkill for now.
> 
> Signed-Off-By: Lee Revell <rlrevell@joe-job.com>

Thanks, applied to CVS.


Takashi


-------------------------------------------------------
This SF.Net email is sponsored by the JBoss Inc.
Get Certified Today * Register for a JBoss Training Course
Free Certification Exam for All Training Attendees Through End of 2005
Visit http://www.jboss.com/services/certification for more information