drm/i915/dp: Reset intel_dp->link_trained before retraining the link

Regularly retraining a link during an atomic commit happens with the
given pipe/link already disabled and hence intel_dp->link_trained being
false. Ensure this also for retraining a DP SST link via direct calls to
the link training functions (vs. an actual commit as for DP MST). So far
nothing depended on this, however the next patch will depend on
link_trained==false for changing the LTTPR mode to non-transparent.

Cc: <[email protected]> # v5.15+
Cc: Ville Syrjälä <[email protected]>
Reviewed-by: Ankit Nautiyal <[email protected]>
Signed-off-by: Imre Deak <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
(cherry picked from commit a4d5ce6)
Signed-off-by: Tvrtko Ursulin <[email protected]>

Author: ideak

drivers/gpu/drm/i915/display/intel_dp.c

@@ -5314,6 +5314,8 @@ static int intel_dp_retrain_link(struct intel_encoder *encoder,
 		const struct intel_crtc_state *crtc_state =
 			to_intel_crtc_state(crtc->base.state);
 
+		intel_dp->link_trained = false;
+
 		intel_dp_check_frl_training(intel_dp);
 		intel_dp_pcon_dsc_configure(intel_dp, crtc_state);
 		intel_dp_start_link_train(NULL, intel_dp, crtc_state);