drm/vc4: dpi: 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>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20220711173939.1132294-30-maxime@cerno.tech

drivers/gpu/drm/vc4/vc4_dpi.c

@@ -316,35 +316,28 @@ static int vc4_dpi_bind(struct device *dev, struct device *master, void *data)
 	if (ret)
 		return ret;
 
-	drm_simple_encoder_init(drm, &dpi->encoder.base, DRM_MODE_ENCODER_DPI);
+	ret = drmm_encoder_init(drm, &dpi->encoder.base,
+				NULL,
+				DRM_MODE_ENCODER_DPI,
+				NULL);
+	if (ret)
+		return ret;
+
 	drm_encoder_helper_add(&dpi->encoder.base, &vc4_dpi_encoder_helper_funcs);
 
 	ret = vc4_dpi_init_bridge(dpi);
 	if (ret)
-		goto err_destroy_encoder;
+		return ret;
 
 	dev_set_drvdata(dev, dpi);
 
 	vc4_debugfs_add_regset32(drm, "dpi_regs", &dpi->regset);
 
 	return 0;
-
-err_destroy_encoder:
-	drm_encoder_cleanup(&dpi->encoder.base);
-	return ret;
-}
-
-static void vc4_dpi_unbind(struct device *dev, struct device *master,
-			   void *data)
-{
-	struct vc4_dpi *dpi = dev_get_drvdata(dev);
-
-	drm_encoder_cleanup(&dpi->encoder.base);
 }
 
 static const struct component_ops vc4_dpi_ops = {
 	.bind   = vc4_dpi_bind,
-	.unbind = vc4_dpi_unbind,
 };
 
 static int vc4_dpi_dev_probe(struct platform_device *pdev)