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Diffstat (limited to 'sound/pci/ac97')
-rw-r--r--sound/pci/ac97/ac97_codec.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/sound/pci/ac97/ac97_codec.c b/sound/pci/ac97/ac97_codec.c
index 94cd989cff20..1f09653dc0f3 100644
--- a/sound/pci/ac97/ac97_codec.c
+++ b/sound/pci/ac97/ac97_codec.c
@@ -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];