[PATCH 05/14] drm/amd/display: Change AUX NACK behavior

[brichang]

From: Ilya Bakoulin <Ilya.Bakoulin at amd.com>

[Why]
Retrying on receiving a NACK can result in long overall EDID read times
in some cases.

[How]
Retry only on DEFER and return immediately on NACK.

Reviewed-by: Aric Cyr <Aric.Cyr at amd.com>
Acked-by: Brian Chang <Brian.Chang at amd.com>
Signed-off-by: Ilya Bakoulin <Ilya.Bakoulin at amd.com>
---
 drivers/gpu/drm/amd/display/dc/dce/dce_aux.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c b/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c
index 919c2c2ba84b..32782ef9ef77 100644
--- a/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c
+++ b/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c
@@ -814,12 +814,6 @@ bool dce_aux_transfer_with_retries(struct ddc_service *ddc,
 								"dce_aux_transfer_with_retries: AUX_RET_SUCCESS: AUX_TRANSACTION_REPLY_I2C_OVER_AUX_DEFER");
 
 				retry_on_defer = true;
-				fallthrough;
-			case AUX_TRANSACTION_REPLY_I2C_OVER_AUX_NACK:
-				if (*payload->reply == AUX_TRANSACTION_REPLY_I2C_OVER_AUX_NACK)
-					DC_TRACE_LEVEL_MESSAGE(DAL_TRACE_LEVEL_INFORMATION,
-								LOG_FLAG_I2cAux_DceAux,
-								"dce_aux_transfer_with_retries: AUX_RET_SUCCESS: AUX_TRANSACTION_REPLY_I2C_OVER_AUX_NACK");
 
 				if (aux_defer_retries >= AUX_MIN_DEFER_RETRIES
 						&& defer_time_in_ms >= AUX_MAX_DEFER_TIMEOUT_MS) {
@@ -848,7 +842,11 @@ bool dce_aux_transfer_with_retries(struct ddc_service *ddc,
 					}
 				}
 				break;
-
+			case AUX_TRANSACTION_REPLY_I2C_OVER_AUX_NACK:
+				DC_TRACE_LEVEL_MESSAGE(DAL_TRACE_LEVEL_INFORMATION,
+							LOG_FLAG_I2cAux_DceAux,
+							"dce_aux_transfer_with_retries: FAILURE: AUX_TRANSACTION_REPLY_I2C_OVER_AUX_NACK");
+				goto fail;
 			case AUX_TRANSACTION_REPLY_I2C_DEFER:
 				DC_TRACE_LEVEL_MESSAGE(DAL_TRACE_LEVEL_INFORMATION,
 							LOG_FLAG_I2cAux_DceAux,
-- 
2.25.1