[ALSA] cmipci: document 'Modem' control version check
Add a comment that explains why the 'Modem' control doesn't work with
newer chips.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
diff --git a/sound/pci/cmipci.c b/sound/pci/cmipci.c
index 8cb3436..bc0a195 100644
--- a/sound/pci/cmipci.c
+++ b/sound/pci/cmipci.c
@@ -2733,6 +2733,10 @@
}
/* card switches */
+ /*
+ * newer chips don't have the register bits to force modem link
+ * detection; the bit that was FLINKON now mutes CH1
+ */
if (cm->chip_version < 39) {
err = snd_ctl_add(cm->card,
snd_ctl_new1(&snd_cmipci_modem_switch, cm));