Re: [PATCH v6 1/4] drm/msm: Guard the QCOM_UBWC_CONFIG select with QCOM_SMEM

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Conditionally selecting QCOM_UBWC_CONFIG without adding `depends on QCOM_UBWC_CONFIG || QCOM_UBWC_CONFIG=n` causes an undefined reference linker error when DRM_MSM is built-in (=y) and QCOM_UBWC_CONFIG is a module (=m).
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--- Patch [1]: [PATCH v6 1/4] drm/msm: Guard the QCOM_UBWC_CONFIG select with QCOM_SMEM ---
commit 353149f56be7035f090eb09914820d684b1f59f4
Author: Daniel Baluta <[email protected]>

drm/msm: Guard the QCOM_UBWC_CONFIG select with QCOM_SMEM

This commit guards the DRM_MSM select of QCOM_UBWC_CONFIG with an
architecture and SMEM check. It also adds a dependency to ensure a
built-in driver is never selected against a modular SMEM.

> diff --git a/drivers/gpu/drm/msm/Kconfig b/drivers/gpu/drm/msm/Kconfig
> index 09469d56513b0..ed1c4775d1e92 100644
> --- a/drivers/gpu/drm/msm/Kconfig
> +++ b/drivers/gpu/drm/msm/Kconfig
[ ... ]
> @@ -22,7 +23,7 @@ config DRM_MSM
>  	select TMPFS
>  	select QCOM_SCM
>  	select QCOM_PAS
> -	select QCOM_UBWC_CONFIG
> +	select QCOM_UBWC_CONFIG if ARCH_QCOM && QCOM_SMEM

[Severity: Low]
Does this conditional select cause an undefined reference linker error when
DRM_MSM is built-in (=y) and QCOM_UBWC_CONFIG is built as a module (=m)?

If the kernel is configured with CONFIG_DRM_MSM=y, CONFIG_COMPILE_TEST=y,
and CONFIG_ARCH_QCOM=n, this conditional select is bypassed. 

If another driver (such as VIDEO_QCOM_IRIS) then selects QCOM_UBWC_CONFIG
as a module, the built-in DRM_MSM driver will fail to link. This happens
because include/linux/soc/qcom/ubwc.h uses IS_ENABLED(CONFIG_QCOM_UBWC_CONFIG)
instead of IS_REACHABLE(), so the header provides an external declaration
rather than a static inline stub.

Should this config also include "depends on QCOM_UBWC_CONFIG ||
QCOM_UBWC_CONFIG=n" to prevent the built-in driver from being selected
against a missing or modular UBWC dependency?

>  	select WANT_DEV_COREDUMP
>  	select SND_SOC_HDMI_CODEC if SND_SOC
>  	select SYNC_FILE

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Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=1