Attachment 41697 Details for Bug 27314 – retry the training with a higher voltage

[patch] retry the training with a higher voltage

0002-drm-radeon-kms-make-dp-link-training-more-robust.patch (text/plain), 2.56 KB, created by Alex Deucher on 2011-01-05 18:37:26 UTC

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Creator: Alex Deucher

Created: 2011-01-05 18:37:26 UTC

Size: 2.56 KB

patch

obsolete

>From 98392a79fd6673e9a75721fa4dd0330b6a113338 Mon Sep 17 00:00:00 2001
>From: Alex Deucher <alexdeucher@gmail.com>
>Date: Wed, 5 Jan 2011 21:31:25 -0500
>Subject: [PATCH 2/2] drm/radeon/kms: make dp link training more robust
>
>If clock recovery succeeded and and link training fails
>during channel equalization, restart training with a higher
>voltage swing and repeat the training.
>
>Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
>---
> drivers/gpu/drm/radeon/atombios_dp.c |   29 ++++++++++++++++++++++++-----
> 1 files changed, 24 insertions(+), 5 deletions(-)
>
>diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
>index c37de73..b1476f2 100644
>--- a/drivers/gpu/drm/radeon/atombios_dp.c
>+++ b/drivers/gpu/drm/radeon/atombios_dp.c
>@@ -591,7 +591,7 @@ void dp_link_train(struct drm_encoder *encoder,
> 	u8 link_configuration[DP_LINK_CONFIGURATION_SIZE];
> 	u8 tries, voltage;
> 	u8 train_set[4];
>-	int i;
>+	int i, restart_tries = 0;
> 
> 	if ((connector->connector_type != DRM_MODE_CONNECTOR_DisplayPort) &&
> 	    (connector->connector_type != DRM_MODE_CONNECTOR_eDP))
>@@ -635,6 +635,11 @@ void dp_link_train(struct drm_encoder *encoder,
> 		dp_set_downspread(radeon_connector, DP_SPREAD_AMP_0_5);
> 	else
> 		dp_set_downspread(radeon_connector, 0x0);
>+
>+	/* set initial vs/emph */
>+	memset(train_set, 0, 4);
>+
>+restart_training:
> 	if (ASIC_IS_DCE4(rdev)) {
> 		/* start training on the source */
> 		atombios_dig_encoder_setup(encoder, ATOM_ENCODER_CMD_DP_LINK_TRAINING_START);
>@@ -649,8 +654,6 @@ void dp_link_train(struct drm_encoder *encoder,
> 					  dig_connector->dp_clock, enc_id, 0);
> 	}
> 
>-	/* set initial vs/emph */
>-	memset(train_set, 0, 4);
> 	udelay(400);
> 	/* set training pattern 1 on the sink */
> 	dp_set_training(radeon_connector, DP_TRAINING_PATTERN_1);
>@@ -739,9 +742,25 @@ void dp_link_train(struct drm_encoder *encoder,
> 		tries++;
> 	}
> 
>-	if (!channel_eq)
>+	if (!channel_eq) {
> 		DRM_ERROR("channel eq failed\n");
>-	else
>+		for (i = 0; i < dig_connector->dp_lane_count; i++) {
>+			if ((train_set[i] & DP_TRAIN_MAX_SWING_REACHED) == 0)
>+				break;
>+		}
>+		/* increase the voltage and try again */
>+		if (i != dig_connector->dp_lane_count) {
>+			u8 v, p;
>+			for (i = 0; i < 4; i++) {
>+				v = train_set[i] & DP_TRAIN_VOLTAGE_SWING_MASK;
>+				p = train_set[i] & DP_TRAIN_PRE_EMPHASIS_MASK;
>+				v++;
>+				train_set[i] = v | p;
>+			}
>+			if (restart_tries++ < 5)
>+				goto restart_training;
>+		}
>+	} else
> 		DRM_DEBUG_KMS("channel eq at voltage %d pre-emphasis %d\n",
> 			  train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK,
> 			  (train_set[0] & DP_TRAIN_PRE_EMPHASIS_MASK)
>-- 
>1.7.1.1
>

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