drm/fbdev-client: Skip DRM clients if modesetting is absent

Recent generations of Tegra have moved the display components outside of
host1x, leading to a device that has no CRTCs attached and hence

drm/fbdev-client: Skip DRM clients if modesetting is absent

Recent generations of Tegra have moved the display components outside of
host1x, leading to a device that has no CRTCs attached and hence doesn't
support any of the modesetting functionality. When this is detected, the
driver clears the DRIVER_MODESET and DRIVER_ATOMIC flags for the device.

Unfortunately, this causes the following errors during boot:

[ 15.418958] ERR KERN drm drm: [drm] *ERROR* Failed to register client: -95
[ 15.425311] WARNING KERN drm drm: [drm] Failed to set up DRM client; error -95

These originate from the fbdev client checking for the presence of the
DRIVER_MODESET flag and returning -EOPNOTSUPP. However, if a driver does
not support DRIVER_MODESET this is entirely expected and the error isn't
helpful.

Prevent this misleading error message by setting up the DRM clients only
if modesetting is enabled.

Changes in v2:
- use DRIVER_MODESET check to avoid registering any clients

Reported-by: Jonathan Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://lore.kernel.org/r/20250613122838.2082334-1-thierry.reding@gmail.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

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drm/client: Include <linux/export.h>

Fixes the compile-time warnings

drivers/gpu/drm/clients/drm_client_setup.c: warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing
drive

drm/client: Include <linux/export.h>

Fixes the compile-time warnings

drivers/gpu/drm/clients/drm_client_setup.c: warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing
drivers/gpu/drm/drm_client.c: warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing
drivers/gpu/drm/drm_client_event.c: warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing
drivers/gpu/drm/drm_client_modeset.c: warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing
drivers/gpu/drm/drm_fb_helper.c: warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing
drivers/gpu/drm/drm_fbdev_dma.c: warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing
drivers/gpu/drm/drm_fbdev_shmem.c: warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing
drivers/gpu/drm/drm_fbdev_ttm.c: warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: a934a57a42f6 ("scripts/misc-check: check missing #include <linux/export.h> when W=1")
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20250612121633.229222-5-tzimmermann@suse.de

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