drm/rcar-du: Use drm_fbdev_generic_setup()

The CMA helper is already using the drm_fb_helper_generic_probe part of
the generic fbdev emulation. This patch makes full use of the generic
fbdev emulation by using its drm_client callbacks. This means that
drm_mode_config_funcs->output_poll_changed and drm_driver->lastclose are
now handled by the emulation code. Additionally fbdev unregister happens
automatically on drm_dev_unregister().

The drm_fbdev_generic_setup() call is put after drm_dev_register() in the
driver. This is done to highlight the fact that fbdev emulation is an
internal client that makes use of the driver, it is not part of the
driver as such. If fbdev setup fails, an error is printed, but the driver
succeeds probing.

drm_fbdev_generic_setup() handles mode_config.num_connector being zero.
In that case it retries fbdev setup on the next .output_poll_changed.

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181128212713.43500-4-noralf@tronnes.org

drivers/gpu/drm/rcar-du/rcar_du_drv.c

@@ -21,6 +21,7 @@
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_fb_cma_helper.h>
+#include <drm/drm_fb_helper.h>
 #include <drm/drm_gem_cma_helper.h>
 
 #include "rcar_du_drv.h"
@@ -392,19 +393,11 @@ MODULE_DEVICE_TABLE(of, rcar_du_of_table);
  * DRM operations
  */
 
-static void rcar_du_lastclose(struct drm_device *dev)
-{
-	struct rcar_du_device *rcdu = dev->dev_private;
-
-	drm_fbdev_cma_restore_mode(rcdu->fbdev);
-}
-
 DEFINE_DRM_GEM_CMA_FOPS(rcar_du_fops);
 
 static struct drm_driver rcar_du_driver = {
 	.driver_features	= DRIVER_GEM | DRIVER_MODESET | DRIVER_PRIME
 				| DRIVER_ATOMIC,
-	.lastclose		= rcar_du_lastclose,
 	.gem_free_object_unlocked = drm_gem_cma_free_object,
 	.gem_vm_ops		= &drm_gem_cma_vm_ops,
 	.prime_handle_to_fd	= drm_gem_prime_handle_to_fd,
@@ -460,9 +453,6 @@ static int rcar_du_remove(struct platform_device *pdev)
 
 	drm_dev_unregister(ddev);
 
-	if (rcdu->fbdev)
-		drm_fbdev_cma_fini(rcdu->fbdev);
-
 	drm_kms_helper_poll_fini(ddev);
 	drm_mode_config_cleanup(ddev);
 
@@ -522,6 +512,8 @@ static int rcar_du_probe(struct platform_device *pdev)
 
 	DRM_INFO("Device %s probed\n", dev_name(&pdev->dev));
 
+	drm_fbdev_generic_setup(ddev, 32);
+
 	return 0;
 
 error:

drivers/gpu/drm/rcar-du/rcar_du_drv.h

@@ -20,7 +20,6 @@
 struct clk;
 struct device;
 struct drm_device;
-struct drm_fbdev_cma;
 struct rcar_du_device;
 
 #define RCAR_DU_FEATURE_CRTC_IRQ_CLOCK	BIT(0)	/* Per-CRTC IRQ and clock */
@@ -78,7 +77,6 @@ struct rcar_du_device {
 	void __iomem *mmio;
 
 	struct drm_device *ddev;
-	struct drm_fbdev_cma *fbdev;
 
 	struct rcar_du_crtc crtcs[RCAR_DU_MAX_CRTCS];
 	unsigned int num_crtcs;

drivers/gpu/drm/rcar-du/rcar_du_kms.c

@@ -255,13 +255,6 @@ rcar_du_fb_create(struct drm_device *dev, struct drm_file *file_priv,
 	return drm_gem_fb_create(dev, file_priv, mode_cmd);
 }
 
-static void rcar_du_output_poll_changed(struct drm_device *dev)
-{
-	struct rcar_du_device *rcdu = dev->dev_private;
-
-	drm_fbdev_cma_hotplug_event(rcdu->fbdev);
-}
-
 /* -----------------------------------------------------------------------------
  * Atomic Check and Update
  */
@@ -308,7 +301,6 @@ static const struct drm_mode_config_helper_funcs rcar_du_mode_config_helper = {
 
 static const struct drm_mode_config_funcs rcar_du_mode_config_funcs = {
 	.fb_create = rcar_du_fb_create,
-	.output_poll_changed = rcar_du_output_poll_changed,
 	.atomic_check = rcar_du_atomic_check,
 	.atomic_commit = drm_atomic_helper_commit,
 };
@@ -543,7 +535,6 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
 
 	struct drm_device *dev = rcdu->ddev;
 	struct drm_encoder *encoder;
-	struct drm_fbdev_cma *fbdev;
 	unsigned int dpad0_sources;
 	unsigned int num_encoders;
 	unsigned int num_groups;
@@ -682,17 +673,5 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
 
 	drm_kms_helper_poll_init(dev);
 
-	if (dev->mode_config.num_connector) {
-		fbdev = drm_fbdev_cma_init(dev, 32,
-					   dev->mode_config.num_connector);
-		if (IS_ERR(fbdev))
-			return PTR_ERR(fbdev);
-
-		rcdu->fbdev = fbdev;
-	} else {
-		dev_info(rcdu->dev,
-			 "no connector found, disabling fbdev emulation\n");
-	}
-
 	return 0;
 }