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Subject[rfc] i810_audio: offset LVI from CIV to avoid stalled start
"Some" OSS applications have trouble with later versions of the
i810_audio driver. Wolfenstein Enemy Territory from idSoftware is
one such application.

I did a little legwork in BK and tracked-down the exact change which
caused the break. The changelog comments are dismissive to the
original code. However, I find that recreating a patch equivalent
to what was removed restores sound to the game.

Anyone have any suggestions for a patch that a) works; and, b)
accounts for the concerns expressed in the changelog?

John

P.S. Here is the problematic patch: (DO NOT TRY TO APPLY THIS)

# This is a BitKeeper generated diff -Nru style patch.
#
# ChangeSet
# 2004/05/11 03:51:54-04:00 herbert@gondor.apana.org.au
# [sound i810] remove bogus CIV_TO_LVI
#
# This patch removes a pair of bogus LVI assignments. The explanation in
# the comment is wrong because the value of PCIB tells the hardware that
# the DMA buffer can be processed even if LVI == CIV.
#
# Setting LVI to CIV + 1 causes overruns when with short writes
# (something that vmware is very fond of).
#
# drivers/sound/i810_audio.c
# 2004/05/11 03:51:52-04:00 herbert@gondor.apana.org.au +0 -10
# [sound i810] remove bogus CIV_TO_LVI
#
# This patch removes a pair of bogus LVI assignments. The explanation in
# the comment is wrong because the value of PCIB tells the hardware that
# the DMA buffer can be processed even if LVI == CIV.
#
# Setting LVI to CIV + 1 causes overruns when with short writes
# (something that vmware is very fond of).
#
diff -Nru a/drivers/sound/i810_audio.c b/drivers/sound/i810_audio.c
--- a/drivers/sound/i810_audio.c 2005-01-14 16:20:27 -05:00
+++ b/drivers/sound/i810_audio.c 2005-01-14 16:20:27 -05:00
@@ -1079,25 +1079,15 @@
else
port += dmabuf->write_channel->port;

- /* if we are currently stopped, then our CIV is actually set to our
- * *last* sg segment and we are ready to wrap to the next. However,
- * if we set our LVI to the last sg segment, then it won't wrap to
- * the next sg segment, it won't even get a start. So, instead, when
- * we are stopped, we set both the LVI value and also we increment
- * the CIV value to the next sg segment to be played so that when
- * we call start_{dac,adc}, things will operate properly
- */
if (!dmabuf->enable && dmabuf->ready) {
if(rec && dmabuf->count < dmabuf->dmasize &&
(dmabuf->trigger & PCM_ENABLE_INPUT))
{
- CIV_TO_LVI(port, 1);
__start_adc(state);
while( !(inb(port + OFF_CR) & ((1<<4) | (1<<2))) ) ;
} else if (!rec && dmabuf->count &&
(dmabuf->trigger & PCM_ENABLE_OUTPUT))
{
- CIV_TO_LVI(port, 1);
__start_dac(state);
while( !(inb(port + OFF_CR) & ((1<<4) | (1<<2))) ) ;
}
--
John W. Linville
linville@tuxdriver.com
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