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    Subject[PATCH 5.10 235/306] drm/exynos: Always initialize mapping in exynos_drm_register_dma()
    Date
    From: Nathan Chancellor <nathan@kernel.org>

    [ Upstream commit c626f3864bbbb28bbe06476b0b497c1330aa4463 ]

    In certain randconfigs, clang warns:

    drivers/gpu/drm/exynos/exynos_drm_dma.c:121:19: warning: variable
    'mapping' is uninitialized when used here [-Wuninitialized]
    priv->mapping = mapping;
    ^~~~~~~
    drivers/gpu/drm/exynos/exynos_drm_dma.c:111:16: note: initialize the
    variable 'mapping' to silence this warning
    void *mapping;
    ^
    = NULL
    1 warning generated.

    This occurs when CONFIG_EXYNOS_IOMMU is enabled and both
    CONFIG_ARM_DMA_USE_IOMMU and CONFIG_IOMMU_DMA are disabled, which makes
    the code look like

    void *mapping;

    if (0)
    mapping = arm_iommu_create_mapping()
    else if (0)
    mapping = iommu_get_domain_for_dev()

    ...
    priv->mapping = mapping;

    Add an else branch that initializes mapping to the -ENODEV error pointer
    so that there is no more warning and the driver does not change during
    runtime.

    Reported-by: kernel test robot <lkp@intel.com>
    Signed-off-by: Nathan Chancellor <nathan@kernel.org>
    Signed-off-by: Inki Dae <inki.dae@samsung.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/gpu/drm/exynos/exynos_drm_dma.c | 2 ++
    1 file changed, 2 insertions(+)

    diff --git a/drivers/gpu/drm/exynos/exynos_drm_dma.c b/drivers/gpu/drm/exynos/exynos_drm_dma.c
    index 0644936afee2..bf33c3084cb4 100644
    --- a/drivers/gpu/drm/exynos/exynos_drm_dma.c
    +++ b/drivers/gpu/drm/exynos/exynos_drm_dma.c
    @@ -115,6 +115,8 @@ int exynos_drm_register_dma(struct drm_device *drm, struct device *dev,
    EXYNOS_DEV_ADDR_START, EXYNOS_DEV_ADDR_SIZE);
    else if (IS_ENABLED(CONFIG_IOMMU_DMA))
    mapping = iommu_get_domain_for_dev(priv->dma_dev);
    + else
    + mapping = ERR_PTR(-ENODEV);

    if (IS_ERR(mapping))
    return PTR_ERR(mapping);
    --
    2.30.2


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