[PATCH] drm: select DRM_KMS_HELPER from DRM_GEM_SHMEM_HELPER

[PATCH] drm: select DRM_KMS_HELPER from DRM_GEM_SHMEM_HELPER

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

In the combination of DRM_KMS_HELPER=m, DRM_GEM_SHMEM_HELPER=y, DRM_FBDEV_EMULATION=y,
The shmem code fails to link against the KMS helpers:

x86_64-linux-ld: vmlinux.o: in function `drm_fbdev_shmem_driver_fbdev_probe':
(.text+0xeec601): undefined reference to `drm_fb_helper_alloc_info'
x86_64-linux-ld: (.text+0xeec633): undefined reference to `drm_fb_helper_fill_info'
x86_64-linux-ld: vmlinux.o: in function `drm_fbdev_shmem_get_page':
drm_fbdev_shmem.c:(.text+0xeec7d2): undefined reference to `drm_gem_fb_get_obj'
x86_64-linux-ld: vmlinux.o: in function `drm_fbdev_shmem_fb_mmap':
drm_fbdev_shmem.c:(.text+0xeec9f6): undefined reference to `drm_gem_fb_get_obj'
x86_64-linux-ld: vmlinux.o: in function `drm_fbdev_shmem_defio_imageblit':
(.rodata+0x5b2288): undefined reference to `drm_fb_helper_check_var'
x86_64-linux-ld: (.rodata+0x5b2290): undefined reference to `drm_fb_helper_set_par'

This can happen for a number of device drivers that select DRM_GEM_SHMEM_HELPER
without also selecting DRM_KMS_HELPER. To work around this, add another select
that forces DRM_KMS_HELPER to be built-in rather than a loadable module, but
only if FBDEV emulation is also enabled.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/gpu/drm/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 0fe99d440bfa..a8d2dffbc82f 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -311,6 +311,7 @@ config DRM_GEM_SHMEM_HELPER
 	depends on DRM && MMU
 	select FB_CORE if DRM_FBDEV_EMULATION
 	select FB_SYSMEM_HELPERS_DEFERRED if DRM_FBDEV_EMULATION
+	select DRM_KMS_HELPER if DRM_FBDEV_EMULATION
 	help
 	  Choose this if you need the GEM shmem helper functions
 
-- 
2.39.5

Re: [PATCH] drm: select DRM_KMS_HELPER from DRM_GEM_SHMEM_HELPER

[Thomas Zimmermann]

Hi

thanks for the patch.

Am 22.01.25 um 07:46 schrieb Arnd Bergmann:
> From: Arnd Bergmann <arnd@arndb.de>
>
> In the combination of DRM_KMS_HELPER=m, DRM_GEM_SHMEM_HELPER=y, DRM_FBDEV_EMULATION=y,
> The shmem code fails to link against the KMS helpers:
>
> x86_64-linux-ld: vmlinux.o: in function `drm_fbdev_shmem_driver_fbdev_probe':
> (.text+0xeec601): undefined reference to `drm_fb_helper_alloc_info'
> x86_64-linux-ld: (.text+0xeec633): undefined reference to `drm_fb_helper_fill_info'
> x86_64-linux-ld: vmlinux.o: in function `drm_fbdev_shmem_get_page':
> drm_fbdev_shmem.c:(.text+0xeec7d2): undefined reference to `drm_gem_fb_get_obj'
> x86_64-linux-ld: vmlinux.o: in function `drm_fbdev_shmem_fb_mmap':
> drm_fbdev_shmem.c:(.text+0xeec9f6): undefined reference to `drm_gem_fb_get_obj'
> x86_64-linux-ld: vmlinux.o: in function `drm_fbdev_shmem_defio_imageblit':
> (.rodata+0x5b2288): undefined reference to `drm_fb_helper_check_var'
> x86_64-linux-ld: (.rodata+0x5b2290): undefined reference to `drm_fb_helper_set_par'
>
> This can happen for a number of device drivers that select DRM_GEM_SHMEM_HELPER
> without also selecting DRM_KMS_HELPER. To work around this, add another select
> that forces DRM_KMS_HELPER to be built-in rather than a loadable module, but
> only if FBDEV emulation is also enabled.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>

with comments below.

> ---
>   drivers/gpu/drm/Kconfig | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 0fe99d440bfa..a8d2dffbc82f 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -311,6 +311,7 @@ config DRM_GEM_SHMEM_HELPER

I expect that DRM_GEM_DMA_HELPER and DRM_GEM_VRAM_HELPER are also affected.

>   	depends on DRM && MMU
>   	select FB_CORE if DRM_FBDEV_EMULATION
>   	select FB_SYSMEM_HELPERS_DEFERRED if DRM_FBDEV_EMULATION
> +	select DRM_KMS_HELPER if DRM_FBDEV_EMULATION

Maybe move the new line before the lines with FB_ to keep it sorted 
alphabetically.

I think this patch fixes

  https://lore.kernel.org/dri-devel/a5a98971-405e-496b-89a4-75a61fd6d898@suse.de/T/#mcc9fa26b2980b93dc688061884119a3dd0277dc5

Could you please add Closes and Reported-by tags?

Best regards
Thomas

>   	help
>   	  Choose this if you need the GEM shmem helper functions
>   

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

Re: [PATCH] drm: select DRM_KMS_HELPER from DRM_GEM_SHMEM_HELPER

[Marc Kleine-Budde]

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On 22.01.2025 08:53:40, Thomas Zimmermann wrote:
[...]

> I think this patch fixes
> 
>  https://lore.kernel.org/dri-devel/a5a98971-405e-496b-89a4-75a61fd6d898@suse.de/T/#mcc9fa26b2980b93dc688061884119a3dd0277dc5

Yes it does! \o/

> Could you please add Closes and Reported-by tags?

Closes: https://lore.kernel.org/all/20250121-greedy-flounder-of-abundance-4d2ee8-mkl@pengutronix.de
Reported-by: Marc Kleine-Budde <mkl@pengutronix.de>
Tested-by: Marc Kleine-Budde <mkl@pengutronix.de>

regards,
Marc

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