drm/i915/dp: Don't stop the link when retraining

On pre-ddi platforms we don't shut down the link when changing link
training parameters. Except when clock recovery fails too hard and we
restart with channel eq training. Which doesn't make a lot of sense
really, since just stopping/restarting the DP port at this point
violates the modeset sequence documented in the Bspec.

So let's tempt fate and try this.

This patch is motivated by a WARN_ON triggered by

commit bc76e320f21f8bd790a72bd5dc06909617432352
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Tue May 20 22:46:50 2014 +0200

    drm/i915: Drop now misleading DDI comment from dp_link_down

References: https://bugs.freedesktop.org/show_bug.cgi?id=85670
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Acked-by: Jani Nikula <jani.nikula@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index ec80e828240efce26559ad5381ee24ed1d5c2e55..5f2c206aef130bfb681879c07d5d26534197f8d8 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3812,7 +3812,6 @@ intel_dp_complete_link_train(struct intel_dp *intel_dp)
 
                /* Try 5 times, then try clock recovery if that fails */
                if (tries > 5) {
-                       intel_dp_link_down(intel_dp);
                        intel_dp_start_link_train(intel_dp);
                        intel_dp_set_link_train(intel_dp, &DP,
                                                training_pattern |