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From 84f4c6b08f0e37320574201bfa16302a000cecdc Mon Sep 17 00:00:00 2001
From: George Shen <george.shen@amd.com>
Date: Fri, 15 Nov 2019 18:56:57 -0500
Subject: [PATCH 4711/4736] drm/amd/display: Increase the number of retries
after AUX DEFER
[Why]
When a timeout occurs after a DEFER, some devices require more retries
than in the case of a regular timeout.
[How]
In a timeout occurrence, check whether a DEFER has occurred before the
timeout and retry MAX_DEFER_RETRIES retries times instead of
MAX_TIMEOUT_RETRIES.
Signed-off-by: George Shen <george.shen@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Abdoulaye Berthe <Abdoulaye.Berthe@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
---
drivers/gpu/drm/amd/display/dc/dce/dce_aux.c | 32 ++++++++++++++------
1 file changed, 22 insertions(+), 10 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 0b9d8c5b9323..5bf6068da717 100644
--- a/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c
+++ b/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c
@@ -608,6 +608,8 @@ bool dce_aux_transfer_with_retries(struct ddc_service *ddc,
uint8_t reply;
bool payload_reply = true;
enum aux_channel_operation_result operation_result;
+ bool retry_on_defer = false;
+
int aux_ack_retries = 0,
aux_defer_retries = 0,
aux_i2c_defer_retries = 0,
@@ -638,8 +640,9 @@ bool dce_aux_transfer_with_retries(struct ddc_service *ddc,
break;
case AUX_TRANSACTION_REPLY_AUX_DEFER:
- case AUX_TRANSACTION_REPLY_I2C_OVER_AUX_NACK:
case AUX_TRANSACTION_REPLY_I2C_OVER_AUX_DEFER:
+ retry_on_defer = true;
+ case AUX_TRANSACTION_REPLY_I2C_OVER_AUX_NACK:
if (++aux_defer_retries >= AUX_MAX_DEFER_RETRIES) {
goto fail;
} else {
@@ -672,15 +675,24 @@ bool dce_aux_transfer_with_retries(struct ddc_service *ddc,
break;
case AUX_CHANNEL_OPERATION_FAILED_TIMEOUT:
- if (++aux_timeout_retries >= AUX_MAX_TIMEOUT_RETRIES)
- goto fail;
- else {
- /*
- * DP 1.4, 2.8.2: AUX Transaction Response/Reply Timeouts
- * According to the DP spec there should be 3 retries total
- * with a 400us wait inbetween each. Hardware already waits
- * for 550us therefore no wait is required here.
- */
+ // Check whether a DEFER had occurred before the timeout.
+ // If so, treat timeout as a DEFER.
+ if (retry_on_defer) {
+ if (++aux_defer_retries >= AUX_MAX_DEFER_RETRIES)
+ goto fail;
+ else if (payload->defer_delay > 0)
+ msleep(payload->defer_delay);
+ } else {
+ if (++aux_timeout_retries >= AUX_MAX_TIMEOUT_RETRIES)
+ goto fail;
+ else {
+ /*
+ * DP 1.4, 2.8.2: AUX Transaction Response/Reply Timeouts
+ * According to the DP spec there should be 3 retries total
+ * with a 400us wait inbetween each. Hardware already waits
+ * for 550us therefore no wait is required here.
+ */
+ }
}
break;
--
2.17.1
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