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[ALSA] ac97: Fix volume control bit size detection for STAC9704. 

AC97 Codec

Signed-off-by: James Courtier-Dutton <James@superbug.co.uk>
This commit is contained in:
James Courtier-Dutton 2005-07-10 12:04:29 +02:00 committed by Jaroslav Kysela
parent 7c1d549aa9
commit c9eab129fc
1 changed files with 5 additions and 0 deletions
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5
sound/pci/ac97/ac97_codec.c
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@ -1078,6 +1078,11 @@ static void check_volume_resolution(ac97_t *ac97, int reg, unsigned char *lo_max
for (i = 0 ; i < ARRAY_SIZE(cbit); i++) {
unsigned short val;
snd_ac97_write(ac97, reg, 0x8080 | cbit[i] | (cbit[i] << 8));
/* Do the read twice due to buffers on some ac97 codecs.
* e.g. The STAC9704 returns exactly what you wrote the the register
* if you read it immediately. This causes the detect routine to fail.
*/
val = snd_ac97_read(ac97, reg);
val = snd_ac97_read(ac97, reg);
if (! *lo_max && (val & 0x7f) == cbit[i])
*lo_max = max[i];