drm/vc4: 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: Eric Anholt <eric@anholt.net>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20180908134648.2582-19-noralf@tronnes.org

drivers/gpu/drm/vc4/vc4_drv.c

@@ -178,7 +178,6 @@ static struct drm_driver vc4_drm_driver = {
 			    DRIVER_RENDER |
 			    DRIVER_PRIME |
 			    DRIVER_SYNCOBJ),
-	.lastclose = drm_fb_helper_lastclose,
 	.open = vc4_open,
 	.postclose = vc4_close,
 	.irq_handler = vc4_irq,
@@ -288,6 +287,8 @@ static int vc4_drm_bind(struct device *dev)
 
 	vc4_kms_load(drm);
 
+	drm_fbdev_generic_setup(drm, 32);
+
 	return 0;
 
 unbind_all:
@@ -307,8 +308,6 @@ static void vc4_drm_unbind(struct device *dev)
 
 	drm_dev_unregister(drm);
 
-	drm_fb_cma_fbdev_fini(drm);
-
 	drm_mode_config_cleanup(drm);
 
 	drm_atomic_private_obj_fini(&vc4->ctm_manager);

drivers/gpu/drm/vc4/vc4_kms.c

@@ -19,8 +19,6 @@
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_plane_helper.h>
-#include <drm/drm_fb_helper.h>
-#include <drm/drm_fb_cma_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
 #include "vc4_drv.h"
 #include "vc4_regs.h"
@@ -394,7 +392,6 @@ vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
 }
 
 static const struct drm_mode_config_funcs vc4_mode_funcs = {
-	.output_poll_changed = drm_fb_helper_output_poll_changed,
 	.atomic_check = vc4_atomic_check,
 	.atomic_commit = vc4_atomic_commit,
 	.fb_create = vc4_fb_create,
@@ -434,9 +431,6 @@ int vc4_kms_load(struct drm_device *dev)
 
 	drm_mode_config_reset(dev);
 
-	if (dev->mode_config.num_connector)
-		drm_fb_cma_fbdev_init(dev, 32, 0);
-
 	drm_kms_helper_poll_init(dev);
 
 	return 0;