[PATCH] drm: rework FB_CORE dependency

[Arnd Bergmann <arnd@kernel.org>]

From: Arnd Bergmann <arnd@arndb.de>

The 'select FB_CORE' statement moved from CONFIG_DRM to DRM_CLIENT_LIB,
but there are now configurations that have code calling into fb_core
as built-in even though the client_lib itself is a loadable module:

x86_64-linux-ld: drivers/gpu/drm/drm_fbdev_shmem.o: in function `drm_fbdev_shmem_driver_fbdev_probe':
drm_fbdev_shmem.c:(.text+0x1fc): undefined reference to `fb_deferred_io_init'
x86_64-linux-ld: drivers/gpu/drm/drm_fbdev_shmem.o: in function `drm_fbdev_shmem_fb_destroy':
drm_fbdev_shmem.c:(.text+0x2e1): undefined reference to `fb_deferred_io_cleanup'
x86_64-linux-ld: drivers/gpu/drm/drm_fbdev_shmem.o: in function `drm_fbdev_shmem_fb_mmap':
drm_fbdev_shmem.c:(.text+0x34c): undefined reference to `fb_deferred_io_mmap'
x86_64-linux-ld: drivers/gpu/drm/drm_fbdev_shmem.o: in function `drm_fbdev_shmem_defio_imageblit':
drm_fbdev_shmem.c:(.text+0x35f): undefined reference to `sys_imageblit'
x86_64-linux-ld: drivers/gpu/drm/drm_fbdev_shmem.o: in function `drm_fbdev_shmem_defio_copyarea':
drm_fbdev_shmem.c:(.text+0x38b): undefined reference to `sys_copyarea'
x86_64-linux-ld: drivers/gpu/drm/drm_fbdev_shmem.o: in function `drm_fbdev_shmem_defio_fillrect':
drm_fbdev_shmem.c:(.text+0x3b7): undefined reference to `sys_fillrect'
x86_64-linux-ld: drivers/gpu/drm/drm_fbdev_shmem.o: in function `drm_fbdev_shmem_defio_write':
drm_fbdev_shmem.c:(.text+0x3e9): undefined reference to `fb_sys_write'
x86_64-linux-ld: drivers/gpu/drm/drm_fbdev_shmem.o: in function `drm_fbdev_shmem_defio_read':
drm_fbdev_shmem.c:(.text+0x413): undefined reference to `fb_sys_read'
x86_64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_set_suspend':
drm_fb_helper.c:(.text+0x2c6): undefined reference to `fb_set_suspend'
x86_64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_resume_worker':
drm_fb_helper.c:(.text+0x2e1): undefined reference to `fb_set_suspend'
x86_64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_alloc_info':
drm_fb_helper.c:(.text+0x33a): undefined reference to `framebuffer_alloc'
x86_64-linux-ld: drm_fb_helper.c:(.text+0x359): undefined reference to `fb_alloc_cmap'
x86_64-linux-ld: drm_fb_helper.c:(.text+0x368): undefined reference to `framebuffer_release'
x86_64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_release_info':
drm_fb_helper.c:(.text+0x3a4): undefined reference to `fb_dealloc_cmap'
x86_64-linux-ld: drm_fb_helper.c:(.text+0x3ab): undefined reference to `framebuffer_release'
x86_64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_unregister_info':
drm_fb_helper.c:(.text+0x3bb): undefined reference to `unregister_framebuffer'
x86_64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `__drm_fb_helper_initial_config_and_unlock':
drm_fb_helper.c:(.text+0xb6d): undefined reference to `register_framebuffer'
x86_64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_set_suspend_unlocked':
drm_fb_helper.c:(.text+0x167a): undefined reference to `fb_set_suspend'

Since the code that calls into fb_core is not actually in the client_lib
module but in other helper libraries, move the 'select' again to the
places that actually call into fb_core, in this case DRM_GEM_SHMEM_HELPER
and DRM_KMS_HELPER.

Fixes: dadd28d4142f ("drm/client: Add client-lib module")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
I have only given this light build testing. It seems sensible on the surface,
but there is a chance that there are additional helpers that need the same
'select'. Moving it into CONFIG_DRM itself would be the safer option, but
that seems to defeat the purpose of the client-lib module.
---
 drivers/gpu/drm/Kconfig | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index a4a092ee70d9..4f21bff6282a 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -98,6 +98,7 @@ config DRM_KUNIT_TEST
 config DRM_KMS_HELPER
 	tristate
 	depends on DRM
+	select FB_CORE if DRM_FBDEV_EMULATION
 	help
 	  CRTC helpers for KMS drivers.
 
@@ -220,7 +221,6 @@ config DRM_CLIENT_LIB
 	tristate
 	depends on DRM
 	select DRM_KMS_HELPER if DRM_FBDEV_EMULATION
-	select FB_CORE if DRM_FBDEV_EMULATION
 	help
 	  This option enables the DRM client library and selects all
 	  modules and components according to the enabled clients.
@@ -372,6 +372,7 @@ config DRM_GEM_SHMEM_HELPER
 	tristate
 	depends on DRM && MMU
 	select FB_SYSMEM_HELPERS_DEFERRED if DRM_FBDEV_EMULATION
+	select FB_CORE if DRM_FBDEV_EMULATION
 	help
 	  Choose this if you need the GEM shmem helper functions
 
-- 
2.39.5