Re: [PATCH] drm: rcar-du: fix linker undefined references

[Randy Dunlap <rdunlap@infradead.org>]

On 4/23/21 2:46 PM, Laurent Pinchart wrote:
> Hi Randy,
> 
> Thank you for the patch.
> 
> On Fri, Apr 23, 2021 at 02:37:27PM -0700, Randy Dunlap wrote:
>> When DRM_RCAR_DU=y and DRM_RCAR_LVDS=m, there are several build errors
>> as reported by 'kernel test robot'. These can be corrected by changing
>> "imply" to "select".
>>
>> In looking at this, the same problem (build errors) happens when
>> DRM_RCAR_DU=y and DRM_RCAR_CMM=m, so again change the "imply" to
>> "select" here as well.
>>
>> These 2 changes fix the following 8 build/link errors:
>>
>> aarch64-linux-ld: drivers/gpu/drm/rcar-du/rcar_du_crtc.o: in function `rcar_du_crtc_atomic_enable':
>> rcar_du_crtc.c:(.text+0x1be8): undefined reference to `rcar_lvds_clk_enable'
>> aarch64-linux-ld: drivers/gpu/drm/rcar-du/rcar_du_crtc.o: in function `rcar_du_crtc_atomic_disable':
>> rcar_du_crtc.c:(.text+0x2438): undefined reference to `rcar_lvds_clk_disable'
>> aarch64-linux-ld: drivers/gpu/drm/rcar-du/rcar_du_drv.o: in function `rcar_du_init':
>> rcar_du_drv.c:(.init.text+0x14): undefined reference to `rcar_du_of_init'
>> aarch64-linux-ld: drivers/gpu/drm/rcar-du/rcar_du_encoder.o: in function `rcar_du_encoder_init':
>> rcar_du_encoder.c:(.text+0x1d4): undefined reference to `rcar_lvds_dual_link'
>>
>> aarch64-linux-ld: drivers/gpu/drm/rcar-du/rcar_du_crtc.o: in function `rcar_du_cmm_setup':
>> rcar_du_crtc.c:(.text+0x380): undefined reference to `rcar_cmm_setup'
>> aarch64-linux-ld: drivers/gpu/drm/rcar-du/rcar_du_crtc.o: in function `rcar_du_crtc_atomic_enable':
>> rcar_du_crtc.c:(.text+0x1c08): undefined reference to `rcar_cmm_enable'
>> aarch64-linux-ld: drivers/gpu/drm/rcar-du/rcar_du_crtc.o: in function `rcar_du_crtc_atomic_disable':
>> rcar_du_crtc.c:(.text+0x231c): undefined reference to `rcar_cmm_disable'
>> aarch64-linux-ld: drivers/gpu/drm/rcar-du/rcar_du_kms.o: in function `rcar_du_modeset_init':
>> rcar_du_kms.c:(.text+0xd08): undefined reference to `rcar_cmm_init'
>>
>> Fixes: e08e934d6c28 ("drm: rcar-du: Add support for CMM")
>> Fixes: 02f2b30032c1 ("drm: rcar-du: lvds: Add API to enable/disable clock output")
>> Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
>> Reported-by: kernel test robot <lkp@intel.com>
>> Cc: Masahiro Yamada <masahiroy@kernel.org>
>> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>> Cc: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
>> Cc: dri-devel@lists.freedesktop.org
>> Cc: linux-renesas-soc@vger.kernel.org
>> Cc: Jacopo Mondi <jacopo+renesas@jmondi.org>
>> ---
>>   drivers/gpu/drm/rcar-du/Kconfig |    4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> --- linux-next-20210420.orig/drivers/gpu/drm/rcar-du/Kconfig
>> +++ linux-next-20210420/drivers/gpu/drm/rcar-du/Kconfig
>> @@ -4,8 +4,8 @@ config DRM_RCAR_DU
>>   	depends on DRM && OF
>>   	depends on ARM || ARM64
>>   	depends on ARCH_RENESAS || COMPILE_TEST
>> -	imply DRM_RCAR_CMM
>> -	imply DRM_RCAR_LVDS
>> +	select DRM_RCAR_CMM
>> +	select DRM_RCAR_LVDS
> 
> No all platforms that integrate a DU have CMM and/or LVDS support, so we
> shouldn't select the automatically.
> 
> Would
> 
> 	depends on DRM_RCAR_CMM || DRM_RCAR_CMM=n
> 	depends on DRM_RCAR_LVDS || DRM_RCAR_LVDS=n
> 

Looks good; I like it, but kconfig does not:

$ xbuild_arm64.sh  oldconfig
make[1]: Entering directory 
'/home/rdunlap/lnx/next/linux-next-20210420/ARM64'
   GEN     Makefile
drivers/gpu/drm/rcar-du/Kconfig:2:error: recursive dependency detected!
drivers/gpu/drm/rcar-du/Kconfig:2:	symbol DRM_RCAR_DU depends on 
DRM_RCAR_CMM
drivers/gpu/drm/rcar-du/Kconfig:17:	symbol DRM_RCAR_CMM depends on 
DRM_RCAR_DU
For a resolution refer to Documentation/kbuild/kconfig-language.rst
subsection "Kconfig recursive dependency limitations"

> work ? I thought that's what "imply" meant, but it seems I got it wrong.
> 
>>   	select DRM_KMS_HELPER
>>   	select DRM_KMS_CMA_HELPER
>>   	select DRM_GEM_CMA_HELPER
> 


Thanks.