[PATCH v2] ALSA: hda/tas2781: Add hardware stabilization delay during firmware load retries

[PATCH v2] ALSA: hda/tas2781: Add hardware stabilization delay during firmware load retries

[Zeliang Li via B4 Relay]

From: Zeliang Li <lizeliang.linux@gmail.com>

During runtime resume transitions, loading calibration data blocks
to the tas2781 amplifier may intermittently trigger transmission
failures or block checksum mismatches (-EAGAIN) due to un-stabilized
power rails or I2C bus glitches.

The loop in tasdev_load_blk() decrements block->nr_retry and attempts
an immediate re-transmission upon receiving -EAGAIN. However, without
any inter-retry delay, all available retry slots are exhausted within
less than a microsecond—long before the hardware can physically
settle. This leads to permanent "ERROR_PRAM_CRCCHK" deadlocks and
silent speakers on modern laptops after resuming media.

Fix this cleanly by introducing a 2ms usleep_range() delay directly
inside the tasdev_load_blk() retry paths prior to each 'continue'
statement. This grants the chip sufficient time to stabilize before
the next transmission attempt without introducing unnecessary latency
on final failures.

Signed-off-by: Zeliang Li <lizeliang.linux@gmail.com>
---
 sound/soc/codecs/tas2781-fmwlib.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/sound/soc/codecs/tas2781-fmwlib.c b/sound/soc/codecs/tas2781-fmwlib.c
index dcbeb9618195..bfabff583d57 100644
--- a/sound/soc/codecs/tas2781-fmwlib.c
+++ b/sound/soc/codecs/tas2781-fmwlib.c
@@ -1849,16 +1849,26 @@ static int tasdev_load_blk(struct tasdevice_priv *tas_priv,
 			}
 		}
 		if (ret == -EAGAIN) {
-			if (block->nr_retry > 0)
+			if (block->nr_retry > 0) {
+				/* Give the hardware time to stabilize before
+				 * next block re-transmission attempt.
+				 */
+				usleep_range(2000, 2500);
 				continue;
+			}
 		} else if (ret < 0) /*err in current device, skip it*/
 			break;
 
 		if (block->is_pchksum_present) {
 			ret = tasdev_block_chksum(tas_priv, block, chn);
 			if (ret == -EAGAIN) {
-				if (block->nr_retry > 0)
+				if (block->nr_retry > 0) {
+					/* Give the bus time to recover after
+					 * a checksum mismatch error.
+					 */
+					usleep_range(2000, 2500);
 					continue;
+				}
 			} else if (ret < 0) /*err in current device, skip it*/
 				break;
 		}

---
base-commit: a5161661ae99f497affa83a5b8654e457cda6267
change-id: 20260815-master-a8aeb8653733

Best regards,
-- 
Zeliang Li <lizeliang.linux@gmail.com>