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* [PATCH AUTOSEL 5.4 079/109] drm/exynos: Always initialize mapping in exynos_drm_register_dma()
       [not found] <20210909115507.147917-1-sashal@kernel.org>
@ 2021-09-09 11:54 ` Sasha Levin
  0 siblings, 0 replies; only message in thread
From: Sasha Levin @ 2021-09-09 11:54 UTC (permalink / raw)
  To: linux-kernel, stable
  Cc: Nathan Chancellor, kernel test robot, Inki Dae, Sasha Levin,
	dri-devel, linux-arm-kernel, linux-samsung-soc,
	clang-built-linux

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 58b89ec11b0e..a3c9d8b9e1a1 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_dma.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_dma.c
@@ -140,6 +140,8 @@ 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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2021-09-09 11:54 ` [PATCH AUTOSEL 5.4 079/109] drm/exynos: Always initialize mapping in exynos_drm_register_dma() Sasha Levin

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