drm/i915/dp: Ensure panel power remains enabled during connector detection

The sink's capabilities, like the DSC caps, depend on the source OUI
written to the sink's DPCD registers and so this OUI value should be
valid for the whole duration of the detection. An eDP sink will reset
this OUI value when the panel power is disabled, so prevent the
disabling - happening by default after a 1 sec idle period - for the
whole duration of detection.

v2: Update the documentation for intel_pps_on(). (Jani)

Cc: Jani Nikula <[e-mail]>
Reviewed-by: Ville Syrjälä <[e-mail]>
Signed-off-by: Imre Deak <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

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

···
 
 	intel_dp_flush_connector_commits(intel_connector);
 
+	intel_pps_vdd_on(intel_dp);
+
 	/* Can't disconnect eDP */
 	if (intel_dp_is_edp(intel_dp))
 		status = edp_detect(intel_dp);
···
 
 		intel_dp_tunnel_disconnect(intel_dp);
 
-		goto out;
+		goto out_unset_edid;
 	}
 
 	ret = intel_dp_tunnel_detect(intel_dp, ctx);
-	if (ret == -EDEADLK)
-		return ret;
+	if (ret == -EDEADLK) {
+		status = ret;
+
+		goto out_vdd_off;
+	}
 
 	if (ret == 1)
 		intel_connector->base.epoch_counter++;
···
 		 * with EDID on it
 		 */
 		status = connector_status_disconnected;
-		goto out;
+		goto out_unset_edid;
 	}
 
 	/*
···
 
 	intel_dp_check_device_service_irq(intel_dp);
 
-out:
+out_unset_edid:
 	if (status != connector_status_connected && !intel_dp->is_mst)
 		intel_dp_unset_edid(intel_dp);
 
···
 						 status,
 						 intel_dp->dpcd,
 						 intel_dp->downstream_ports);
+out_vdd_off:
+	intel_pps_vdd_off(intel_dp);
+
 	return status;
 }
 

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

···
 }
 
 /*
- * Must be paired with intel_pps_off().
+ * Must be paired with intel_pps_vdd_off() or - to disable
+ * both VDD and panel power - intel_pps_off().
  * Nested calls to these functions are not allowed since
  * we drop the lock. Caller must use some higher level
  * locking to prevent nested calls from other threads.
···
 		intel_pps_vdd_off_sync_unlocked(intel_dp);
 	else
 		edp_panel_vdd_schedule_off(intel_dp);
+}
+
+void intel_pps_vdd_off(struct intel_dp *intel_dp)
+{
+	intel_wakeref_t wakeref;
+
+	if (!intel_dp_is_edp(intel_dp))
+		return;
+
+	with_intel_pps_lock(intel_dp, wakeref)
+		intel_pps_vdd_off_unlocked(intel_dp, false);
 }
 
 void intel_pps_on_unlocked(struct intel_dp *intel_dp)

drivers/gpu/drm/i915/display/intel_pps.h

···
 void intel_pps_check_power_unlocked(struct intel_dp *intel_dp);
 
 void intel_pps_vdd_on(struct intel_dp *intel_dp);
+void intel_pps_vdd_off(struct intel_dp *intel_dp);
 void intel_pps_on(struct intel_dp *intel_dp);
 void intel_pps_off(struct intel_dp *intel_dp);
 void intel_pps_vdd_off_sync(struct intel_dp *intel_dp);