drm/imx/dcss: Run DRM default client setup

Call drm_client_setup() to run the kernel's default client setup
for DRM. Set fbdev_probe in struct drm_driver, so that the client
setup can start the common fbdev client.

The dcss driver specifies a preferred color mode of 32. As this
is the default if no format has been given, leave it out entirely.

v5:
- select DRM_CLIENT_SELECTION

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240924071734.98201-20-tzimmermann@suse.de

drivers/gpu/drm/imx/dcss/Kconfig

@@ -1,6 +1,7 @@
 config DRM_IMX_DCSS
 	tristate "i.MX8MQ DCSS"
 	select IMX_IRQSTEER
+	select DRM_CLIENT_SELECTION
 	select DRM_KMS_HELPER
 	select DRM_DISPLAY_HELPER
 	select DRM_BRIDGE_CONNECTOR

drivers/gpu/drm/imx/dcss/dcss-kms.c

@@ -6,6 +6,7 @@
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge_connector.h>
+#include <drm/drm_client_setup.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_fbdev_dma.h>
 #include <drm/drm_gem_dma_helper.h>
@@ -28,6 +29,7 @@ static const struct drm_mode_config_funcs dcss_drm_mode_config_funcs = {
 static const struct drm_driver dcss_kms_driver = {
 	.driver_features	= DRIVER_MODESET | DRIVER_GEM | DRIVER_ATOMIC,
 	DRM_GEM_DMA_DRIVER_OPS,
+	DRM_FBDEV_DMA_DRIVER_OPS,
 	.fops			= &dcss_cma_fops,
 	.name			= "imx-dcss",
 	.desc			= "i.MX8MQ Display Subsystem",
@@ -145,7 +147,7 @@ struct dcss_kms_dev *dcss_kms_attach(struct dcss_dev *dcss)
 	if (ret)
 		goto cleanup_crtc;
 
-	drm_fbdev_dma_setup(drm, 32);
+	drm_client_setup(drm, NULL);
 
 	return kms;