drm/fsl-dcu: 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.

Cc: Stefan Agner <stefan@agner.ch>
Cc: Alison Wang <alison.wang@nxp.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Stefan Agner <stefan@agner.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20181025201340.34227-3-noralf@tronnes.org

drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c

@@ -26,6 +26,7 @@
 #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 <drm/drm_modeset_helper.h>
 
@@ -89,20 +90,11 @@ static int fsl_dcu_load(struct drm_device *dev, unsigned long flags)
 			"Invalid legacyfb_depth.  Defaulting to 24bpp\n");
 		legacyfb_depth = 24;
 	}
-	fsl_dev->fbdev = drm_fbdev_cma_init(dev, legacyfb_depth, 1);
-	if (IS_ERR(fsl_dev->fbdev)) {
-		ret = PTR_ERR(fsl_dev->fbdev);
-		fsl_dev->fbdev = NULL;
-		goto done;
-	}
 
 	return 0;
 done:
 	drm_kms_helper_poll_fini(dev);
 
-	if (fsl_dev->fbdev)
-		drm_fbdev_cma_fini(fsl_dev->fbdev);
-
 	drm_mode_config_cleanup(dev);
 	drm_irq_uninstall(dev);
 	dev->dev_private = NULL;
@@ -112,14 +104,9 @@ static int fsl_dcu_load(struct drm_device *dev, unsigned long flags)
 
 static void fsl_dcu_unload(struct drm_device *dev)
 {
-	struct fsl_dcu_drm_device *fsl_dev = dev->dev_private;
-
 	drm_atomic_helper_shutdown(dev);
 	drm_kms_helper_poll_fini(dev);
 
-	if (fsl_dev->fbdev)
-		drm_fbdev_cma_fini(fsl_dev->fbdev);
-
 	drm_mode_config_cleanup(dev);
 	drm_irq_uninstall(dev);
 
@@ -147,19 +134,11 @@ static irqreturn_t fsl_dcu_drm_irq(int irq, void *arg)
 	return IRQ_HANDLED;
 }
 
-static void fsl_dcu_drm_lastclose(struct drm_device *dev)
-{
-	struct fsl_dcu_drm_device *fsl_dev = dev->dev_private;
-
-	drm_fbdev_cma_restore_mode(fsl_dev->fbdev);
-}
-
 DEFINE_DRM_GEM_CMA_FOPS(fsl_dcu_drm_fops);
 
 static struct drm_driver fsl_dcu_drm_driver = {
 	.driver_features	= DRIVER_HAVE_IRQ | DRIVER_GEM | DRIVER_MODESET
 				| DRIVER_PRIME | DRIVER_ATOMIC,
-	.lastclose		= fsl_dcu_drm_lastclose,
 	.load			= fsl_dcu_load,
 	.unload			= fsl_dcu_unload,
 	.irq_handler		= fsl_dcu_drm_irq,
@@ -355,6 +334,8 @@ static int fsl_dcu_drm_probe(struct platform_device *pdev)
 	if (ret < 0)
 		goto put;
 
+	drm_fbdev_generic_setup(drm, legacyfb_depth);
+
 	return 0;
 
 put:

drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h

@@ -191,7 +191,6 @@ struct fsl_dcu_drm_device {
 	/*protects hardware register*/
 	spinlock_t irq_lock;
 	struct drm_device *drm;
-	struct drm_fbdev_cma *fbdev;
 	struct drm_crtc crtc;
 	struct drm_encoder encoder;
 	struct fsl_dcu_drm_connector connector;