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From: <>
Cc: <>
Subject: FAILED: patch "[PATCH] drm/i915: Disable LTTPR support when the LTTPR rev < 1.4" failed to apply to 5.11-stable tree
Date: Sat, 27 Mar 2021 15:20:10 +0100	[thread overview]
Message-ID: <> (raw)

The patch below does not apply to the 5.11-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <>.


greg k-h

------------------ original commit in Linus's tree ------------------

From ab03631087f5c296030dd86265ea02dcdacc6802 Mon Sep 17 00:00:00 2001
From: Imre Deak <>
Date: Wed, 17 Mar 2021 20:49:01 +0200
Subject: [PATCH] drm/i915: Disable LTTPR support when the LTTPR rev < 1.4
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

By the specification the 0xF0000 - 0xF02FF range is only valid if the
LTTPR revision at 0xF0000 is at least 1.4. Disable the LTTPR support

Fixes: 7b2a4ab8b0ef ("drm/i915: Switch to LTTPR transparent mode link training")
Cc: <> # v5.11
Cc: Ville Syrjälä <>
Signed-off-by: Imre Deak <>
Reviewed-by: Ville Syrjälä <>
(cherry picked from commit 1663ad4936e0679443a315fe342f99636a2420dd)
Signed-off-by: Rodrigo Vivi <>

diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
index c10e81a3d64f..be6ac0dd846e 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
@@ -99,17 +99,23 @@ static bool intel_dp_read_lttpr_common_caps(struct intel_dp *intel_dp)
 		return false;
 	if (drm_dp_read_lttpr_common_caps(&intel_dp->aux,
-					  intel_dp->lttpr_common_caps) < 0) {
-		intel_dp_reset_lttpr_common_caps(intel_dp);
-		return false;
-	}
+					  intel_dp->lttpr_common_caps) < 0)
+		goto reset_caps;
 		    "LTTPR common capabilities: %*ph\n",
+	/* The minimum value of LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV is 1.4 */
+	if (intel_dp->lttpr_common_caps[0] < 0x14)
+		goto reset_caps;
 	return true;
+	intel_dp_reset_lttpr_common_caps(intel_dp);
+	return false;
 static bool

             reply	other threads:[~2021-03-27 14:20 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-27 14:20 gregkh [this message]
2021-05-12  9:48 gregkh

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