drm/mxsfb: 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: Marek Vasut <marex@denx.de>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20181128212713.43500-3-noralf@tronnes.org

drivers/gpu/drm/mxsfb/mxsfb_drv.c

@@ -263,23 +263,12 @@ static int mxsfb_load(struct drm_device *drm, unsigned long flags)
 
 	drm_kms_helper_poll_init(drm);
 
-	mxsfb->fbdev = drm_fbdev_cma_init(drm, 32,
-					  drm->mode_config.num_connector);
-	if (IS_ERR(mxsfb->fbdev)) {
-		ret = PTR_ERR(mxsfb->fbdev);
-		mxsfb->fbdev = NULL;
-		dev_err(drm->dev, "Failed to init FB CMA area\n");
-		goto err_cma;
-	}
-
 	platform_set_drvdata(pdev, drm);
 
 	drm_helper_hpd_irq_event(drm);
 
 	return 0;
 
-err_cma:
-	drm_irq_uninstall(drm);
 err_irq:
 	drm_panel_detach(mxsfb->panel);
 err_vblank:
@@ -290,11 +279,6 @@ static int mxsfb_load(struct drm_device *drm, unsigned long flags)
 
 static void mxsfb_unload(struct drm_device *drm)
 {
-	struct mxsfb_drm_private *mxsfb = drm->dev_private;
-
-	if (mxsfb->fbdev)
-		drm_fbdev_cma_fini(mxsfb->fbdev);
-
 	drm_kms_helper_poll_fini(drm);
 	drm_mode_config_cleanup(drm);
 
@@ -307,13 +291,6 @@ static void mxsfb_unload(struct drm_device *drm)
 	pm_runtime_disable(drm->dev);
 }
 
-static void mxsfb_lastclose(struct drm_device *drm)
-{
-	struct mxsfb_drm_private *mxsfb = drm->dev_private;
-
-	drm_fbdev_cma_restore_mode(mxsfb->fbdev);
-}
-
 static void mxsfb_irq_preinstall(struct drm_device *drm)
 {
 	struct mxsfb_drm_private *mxsfb = drm->dev_private;
@@ -347,7 +324,6 @@ static struct drm_driver mxsfb_driver = {
 	.driver_features	= DRIVER_GEM | DRIVER_MODESET |
 				  DRIVER_PRIME | DRIVER_ATOMIC |
 				  DRIVER_HAVE_IRQ,
-	.lastclose		= mxsfb_lastclose,
 	.irq_handler		= mxsfb_irq_handler,
 	.irq_preinstall		= mxsfb_irq_preinstall,
 	.irq_uninstall		= mxsfb_irq_preinstall,
@@ -412,6 +388,8 @@ static int mxsfb_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_unload;
 
+	drm_fbdev_generic_setup(drm, 32);
+
 	return 0;
 
 err_unload:

drivers/gpu/drm/mxsfb/mxsfb_drv.h

@@ -37,7 +37,6 @@ struct mxsfb_drm_private {
 	struct drm_simple_display_pipe	pipe;
 	struct drm_connector		connector;
 	struct drm_panel		*panel;
-	struct drm_fbdev_cma		*fbdev;
 };
 
 int mxsfb_setup_crtc(struct drm_device *dev);