drm/arm/hdlcd: 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: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Liviu Dudau <liviu.dudau@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180908134648.2582-9-noralf@tronnes.org

drivers/gpu/drm/arm/hdlcd_drv.c

@@ -103,7 +103,6 @@ static int hdlcd_load(struct drm_device *drm, unsigned long flags)
 
 static const struct drm_mode_config_funcs hdlcd_mode_config_funcs = {
 	.fb_create = drm_gem_fb_create,
-	.output_poll_changed = drm_fb_helper_output_poll_changed,
 	.atomic_check = drm_atomic_helper_check,
 	.atomic_commit = drm_atomic_helper_commit,
 };
@@ -233,7 +232,6 @@ static struct drm_driver hdlcd_driver = {
 	.driver_features = DRIVER_HAVE_IRQ | DRIVER_GEM |
 			   DRIVER_MODESET | DRIVER_PRIME |
 			   DRIVER_ATOMIC,
-	.lastclose = drm_fb_helper_lastclose,
 	.irq_handler = hdlcd_irq,
 	.irq_preinstall = hdlcd_irq_preinstall,
 	.irq_postinstall = hdlcd_irq_postinstall,
@@ -308,19 +306,15 @@ static int hdlcd_drm_bind(struct device *dev)
 	drm_mode_config_reset(drm);
 	drm_kms_helper_poll_init(drm);
 
-	ret = drm_fb_cma_fbdev_init(drm, 32, 0);
-	if (ret)
-		goto err_fbdev;
-
 	ret = drm_dev_register(drm, 0);
 	if (ret)
 		goto err_register;
 
+	drm_fbdev_generic_setup(drm, 32);
+
 	return 0;
 
 err_register:
-	drm_fb_cma_fbdev_fini(drm);
-err_fbdev:
 	drm_kms_helper_poll_fini(drm);
 err_vblank:
 	pm_runtime_disable(drm->dev);
@@ -346,7 +340,6 @@ static void hdlcd_drm_unbind(struct device *dev)
 	struct hdlcd_drm_private *hdlcd = drm->dev_private;
 
 	drm_dev_unregister(drm);
-	drm_fb_cma_fbdev_fini(drm);
 	drm_kms_helper_poll_fini(drm);
 	component_unbind_all(dev, drm);
 	of_node_put(hdlcd->crtc.port);