ASoC: apple: mca: Add delay after configuring clock

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 <[email protected]>
AsahiLinux · Dec 14, 2023 · cb05ac2 · cb05ac2
1 parent ea38732
commit cb05ac2
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/sound/soc/apple/mca.c b/sound/soc/apple/mca.c
@@ -225,6 +225,12 @@ 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(10);
 		break;
 	default:
 		break;