Re: [PATCH v2 2/2] drm/fbdev: Move fbdev helpers into client library

[Thomas Zimmermann <tzimmermann@suse.de>]

Am 24.09.26 um 11:43 schrieb sashiko-bot@kernel.org:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Low] drm: missing DRM_CLIENT_LIB selection in memory helpers causes linker error
> --
>
> commit b0f3c606cfc59f0c56cd9be7e3349abc72f97a64
> Author: Thomas Zimmermann <tzimmermann@suse.de>
>
> drm/fbdev: Move fbdev helpers into client library
>
> DRM's fbdev helpers are for the fbdev-emulation clients. Move them
> into the client-library module. Fix include statements throughout
> DRM drivers.
>
>> diff --git a/drivers/gpu/drm/clients/Makefile b/drivers/gpu/drm/clients/Makefile
>> index c16addbc327f0..1304ff358509d 100644
>> --- a/drivers/gpu/drm/clients/Makefile
>> +++ b/drivers/gpu/drm/clients/Makefile
>> @@ -4,5 +4,6 @@ subdir-ccflags-y += -I$(src)/..
>>   
>>   drm_client_lib-y := drm_client_setup.o
>>   drm_client_lib-$(CONFIG_DRM_CLIENT_LOG) += drm_log.o
>> -drm_client_lib-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fbdev_client.o
>> +drm_client_lib-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fbdev_client.o \
>> +						drm_fbdev_helper.o
> [Severity: Low]
> Since drm_fbdev_helper.o is now built into drm_client_lib, can this cause a
> linker error for built-in memory helpers?
>
> If CONFIG_DRM_FBDEV_EMULATION=y and a driver selects DRM_GEM_DMA_HELPER=y,
> but CONFIG_DRM_CLIENT_SELECTION=m (selected only by modular drivers),
> drm_client_lib.ko will be built as a module while drm_fbdev_dma.o becomes
> built-in.
>
> This would lead to undefined references to fbdev helper functions (e.g.,
> drm_fb_helper_fini) during vmlinux linkage.
>
> Do the memory helpers in drivers/gpu/drm/Kconfig (DRM_GEM_DMA_HELPER,
> DRM_GEM_SHMEM_HELPER, DRM_TTM_HELPER) need to explicitly select
> DRM_CLIENT_LIB when DRM_FBDEV_EMULATION is enabled to prevent this?

To answer that question: yes they do. And I forgot that they already do 
the same for DRM_KMS_HELPER because of this dependency. [1] The 
KMS-helper rule simply needs to be replaced with the client-lib. The 
memory managers do not use the three module parameters that remain in 
drm_kms_helper.ko . No need for a dependency there.

>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Stefan Gaiser, Jochen Jaser, Abhinav Puri, (HRB 36809, AG Nürnberg)