Re: [PATCH v4 0/3] soc: qcom: ubwc: Fix link error

[Nathan Chancellor <nathan@kernel.org>]

Hi Daniel,

On Wed, Aug 12, 2026 at 06:19:31PM +0300, Daniel Baluta wrote:
> Fix link error caused by the fact that drivers/soc/qcom/ubwc_config.c
> enabled via QCOM_UBWC_CONFIG uses unconditionally symbols from
> drivers/soc/qcom/smem.c enabled via CONFIG_QCOM_SMEM.
> 
> Changes since v3:
> - fix issues pointed by sashiko https://sashiko.dev/#/patchset/20260812130421.670527-1-daniel.baluta%40nxp.com
>  - add new patches 2/3 in order to fix unmet dependcy for VIDEO_QCOM_IRIS
>  - Use IS_REACHABLE instead of IS_ENABLED to avoid the situation we use
>    some symbols in builtin kernel but their definitions sits in a
> module.
> 
> Remark for Dmitry, at this point I think v1 would have been a better
> option.
> Link to v1:
> -	https://lore.kernel.org/imx/1521da8e-18df-4d7b-a255-5ca133bd5ccc@oss.nxp.com/T/#t
> 
> 
> 
> Daniel Baluta (3):
>   soc: qcom: ubwc: Fix link error when QCOM_SMEM=n
>   media: iris: Fix unmet dependency when QCOM_SMEM=n

I think this patch should come first since you introduce the QCOM_SMEM
dependency that requires this change in the first patch, which could
mess with bisects. I would personally add the 'if' condition to the
'select QCOM_UBWC_CONFIG' statements in one patch then add the QCOM_SMEM
dependency to QCOM_UBWC_CONFIG in a separate patch.

>   soc: qcom: ubwc: Use IS_REACHABLE() instead of IS_ENABLED()

Even with this series applied, I see

  $ cat allno.config
  CONFIG_ARCH_MULTI_V7=y
  CONFIG_ARCH_QCOM=y
  CONFIG_DRM=y
  CONFIG_DRM_MSM=y
  CONFIG_DRM_MSM_DPU=y
  CONFIG_IOMMU_SUPPORT=y
  CONFIG_MAILBOX=y
  CONFIG_MMU=y
  CONFIG_PM=y
  CONFIG_QCOM_AOSS_QMP=y
  CONFIG_QCOM_LLCC=y
  CONFIG_QCOM_OCMEM=y

  $ make -skj"$(nproc)" ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- KCONFIG_ALLCONFIG=1 allnoconfig drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp_v13.o
  In file included from drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp_v13.c:7:
  include/linux/soc/qcom/ubwc.h: In function 'qcom_ubwc_config_get_data':
  include/linux/soc/qcom/ubwc.h:45:16: error: implicit declaration of function 'ERR_PTR' [-Wimplicit-function-declaration]
     45 |         return ERR_PTR(-EOPNOTSUPP);
        |                ^~~~~~~
  include/linux/soc/qcom/ubwc.h:45:25: error: 'EOPNOTSUPP' undeclared (first use in this function)
     45 |         return ERR_PTR(-EOPNOTSUPP);
        |                         ^~~~~~~~~~
  include/linux/soc/qcom/ubwc.h:45:25: note: each undeclared identifier is reported only once for each function it appears in
  In file included from include/linux/cleanup.h:6,
                   from include/linux/irqflags.h:17,
                   from arch/arm/include/asm/bitops.h:28,
                   from include/linux/bitops.h:67,
                   from include/linux/kernel.h:23,
                   from drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h:10,
                   from drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.h:8,
                   from drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp_v13.c:9:
  include/linux/err.h: At top level:
  include/linux/err.h:39:44: error: conflicting types for 'ERR_PTR'; have 'void *(long int)'
     39 | static __always_inline void * __must_check ERR_PTR(long error)
        |                                            ^~~~~~~
  include/linux/soc/qcom/ubwc.h:45:16: note: previous implicit declaration of 'ERR_PTR' with type 'int()'
     45 |         return ERR_PTR(-EOPNOTSUPP);
        |                ^~~~~~~

Adding '#include <linux/err.h>' to include/linux/soc/qcom/ubwc.h appears
to resolve that for me.

-- 
Cheers,
Nathan