drm/vc4: hdmi: Switch to DRM-managed encoder initialization

The current code will call drm_encoder_cleanup() when the device is
unbound. However, by then, there might still be some references held to
that encoder, including by the userspace that might still have the DRM
device open.

Let's switch to a DRM-managed initialization to clean up after ourselves
only once the DRM device has been last closed.
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20220711173939.1132294-40-maxime@cerno.tech

drivers/gpu/drm/vc4/vc4_hdmi.c

@@ -2984,12 +2984,18 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
 		clk_prepare_enable(vc4_hdmi->pixel_bvb_clock);
 	}
 
-	drm_simple_encoder_init(drm, encoder, DRM_MODE_ENCODER_TMDS);
+	ret = drmm_encoder_init(drm, encoder,
+				NULL,
+				DRM_MODE_ENCODER_TMDS,
+				NULL);
+	if (ret)
+		goto err_put_runtime_pm;
+
 	drm_encoder_helper_add(encoder, &vc4_hdmi_encoder_helper_funcs);
 
 	ret = vc4_hdmi_connector_init(drm, vc4_hdmi);
 	if (ret)
-		goto err_destroy_encoder;
+		goto err_put_runtime_pm;
 
 	ret = vc4_hdmi_hotplug_init(vc4_hdmi);
 	if (ret)
@@ -3017,8 +3023,7 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
 	vc4_hdmi_hotplug_exit(vc4_hdmi);
 err_destroy_conn:
 	drm_connector_cleanup(&vc4_hdmi->connector);
-err_destroy_encoder:
-	drm_encoder_cleanup(encoder);
+err_put_runtime_pm:
 	pm_runtime_put_sync(dev);
 err_disable_runtime_pm:
 	pm_runtime_disable(dev);
@@ -3061,7 +3066,6 @@ static void vc4_hdmi_unbind(struct device *dev, struct device *master,
 	vc4_hdmi_cec_exit(vc4_hdmi);
 	vc4_hdmi_hotplug_exit(vc4_hdmi);
 	drm_connector_cleanup(&vc4_hdmi->connector);
-	drm_encoder_cleanup(&vc4_hdmi->encoder.base);
 
 	pm_runtime_disable(dev);