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 <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From d2b9935d65dab6e92beb33c150c1a6ded14ab670 Mon Sep 17 00:00:00 2001
From: Imre Deak <imre.deak@xxxxxxxxx>
Date: Tue, 13 Apr 2021 02:24:12 +0300
Subject: [PATCH] drm/i915: Fix modesetting in case of unexpected AUX timeouts
MIME-Version: 1.0
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In case AUX failures happen unexpectedly during a modeset, the driver
should still complete the modeset. In particular the driver should
perform the link training sequence steps even in case of an AUX failure,
as this sequence also includes port initialization steps. Not doing that
can leave the port/pipe in a broken state and lead for instance to a
flip done timeout.
Fix this by continuing with link training (in a no-LTTPR mode) if the
DPRX DPCD readout failed for some reason at the beginning of link
training. After a successful connector detection we already have the
DPCD read out and cached, so the failed repeated read for it should not
cause a problem. Note that a partial AUX read could in theory partly
overwrite the cached DPCD (and return error) but this overwrite should
not happen if the returned values are corrupted (due to a timeout or
some other IO error).
Kudos to Ville to root cause the problem.
Fixes: 7dffbdedb96a ("drm/i915: Disable LTTPR support when the DPCD rev < 1.4")
References: https://gitlab.freedesktop.org/drm/intel/-/issues/3308
Cc: stable@xxxxxxxxxxxxxxx # 5.11
Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20210412232413.2755054-1-imre.deak@xxxxxxxxx
(cherry picked from commit e42e7e585984b85b0fb9dd1fefc85ee4800ca629)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
[adjusted Fixes: tag]
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 be6ac0dd846e..2ed309534e97 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
@@ -848,7 +848,8 @@ void intel_dp_start_link_train(struct intel_dp *intel_dp,
int lttpr_count = intel_dp_init_lttpr_and_dprx_caps(intel_dp);
if (lttpr_count < 0)
- return;
+ /* Still continue with enabling the port and link training. */
+ lttpr_count = 0;
if (!intel_dp_link_train_all_phys(intel_dp, crtc_state, lttpr_count))
intel_dp_schedule_fallback_link_training(intel_dp, crtc_state);
