From: Hector Martin <marcan@marcan.st>
Right after the early FE setup, ADMAC gets told to start the DMA. This
can end up in a weird "slip" state with the channels transposed. Waiting
a bit fixes this; presumably this allows the clock to stabilize.
Signed-off-by: Hector Martin <marcan@marcan.st>
Signed-off-by: James Calligeros <jcalligeros99@gmail.com>
---
sound/soc/apple/mca.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/sound/soc/apple/mca.c b/sound/soc/apple/mca.c
index 25d04b3d8a57a8551f2ac1c0cd2dbf2997d907e8..1c664c204504174df1d0af3cafbe25235c678687 100644
--- a/sound/soc/apple/mca.c
+++ b/sound/soc/apple/mca.c
@@ -231,6 +231,12 @@ static void mca_fe_early_trigger(struct snd_pcm_substream *substream, int cmd,
FIELD_PREP(SERDES_CONF_SYNC_SEL, 0));
mca_modify(cl, serdes_conf, SERDES_CONF_SYNC_SEL,
FIELD_PREP(SERDES_CONF_SYNC_SEL, cl->no + 1));
+ /*
+ * ADMAC gets started right after this. This delay seems
+ * to be needed for that to be reliable, e.g. ensure the
+ * clock is stable?
+ */
+ udelay(100);
break;
default:
break;
--
2.49.0