drm/bridge: analogix_dp: Enable autosuspend

DP AUX transactions can consist of many short operations. There's no
need to power things up/down in short intervals.

I pick an arbitrary 100ms; for the systems I'm testing (Rockchip
RK3399), runtime-PM transitions only take a few microseconds.
Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220301181107.v4.2.I48b18ab197c9b649d376cf8cfd934e59d338f86d@changeid

drivers/gpu/drm/bridge/analogix/analogix_dp_core.c

@@ -1119,9 +1119,7 @@ static int analogix_dp_get_modes(struct drm_connector *connector)
 			return 0;
 		}
 
-		pm_runtime_get_sync(dp->dev);
 		edid = drm_get_edid(connector, &dp->aux.ddc);
-		pm_runtime_put(dp->dev);
 		if (edid) {
 			drm_connector_update_edid_property(&dp->connector,
 							   edid);
@@ -1642,7 +1640,8 @@ static ssize_t analogix_dpaux_transfer(struct drm_dp_aux *aux,
 
 	ret = analogix_dp_transfer(dp, msg);
 out:
-	pm_runtime_put(dp->dev);
+	pm_runtime_mark_last_busy(dp->dev);
+	pm_runtime_put_autosuspend(dp->dev);
 
 	return ret;
 }
@@ -1775,6 +1774,8 @@ int analogix_dp_bind(struct analogix_dp_device *dp, struct drm_device *drm_dev)
 	if (ret)
 		return ret;
 
+	pm_runtime_use_autosuspend(dp->dev);
+	pm_runtime_set_autosuspend_delay(dp->dev, 100);
 	pm_runtime_enable(dp->dev);
 
 	ret = analogix_dp_create_bridge(drm_dev, dp);
@@ -1786,6 +1787,7 @@ int analogix_dp_bind(struct analogix_dp_device *dp, struct drm_device *drm_dev)
 	return 0;
 
 err_disable_pm_runtime:
+	pm_runtime_dont_use_autosuspend(dp->dev);
 	pm_runtime_disable(dp->dev);
 	drm_dp_aux_unregister(&dp->aux);
 
@@ -1804,6 +1806,7 @@ void analogix_dp_unbind(struct analogix_dp_device *dp)
 	}
 
 	drm_dp_aux_unregister(&dp->aux);
+	pm_runtime_dont_use_autosuspend(dp->dev);
 	pm_runtime_disable(dp->dev);
 }
 EXPORT_SYMBOL_GPL(analogix_dp_unbind);