From: Nathan Chancellor natechancellor@gmail.com
[ Upstream commit a63141e31764f8daf3f29e8e2d450dcf9199d1c8 ]
Commit b0f3cd3191cd ("drm/amdgpu: remove unnecessary JPEG2.0 code from VCN2.0") introduced a new clang warning in the vcn_v2_0_stop function:
../drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1082:2: warning: variable 'r' is used uninitialized whenever 'while' loop exits because its condition is false [-Wsometimes-uninitialized] SOC15_WAIT_ON_RREG(VCN, 0, mmUVD_STATUS, UVD_STATUS__IDLE, 0x7, r); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ../drivers/gpu/drm/amd/amdgpu/../amdgpu/soc15_common.h:55:10: note: expanded from macro 'SOC15_WAIT_ON_RREG' while ((tmp_ & (mask)) != (expected_value)) { \ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ../drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1083:6: note: uninitialized use occurs here if (r) ^ ../drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1082:2: note: remove the condition if it is always true SOC15_WAIT_ON_RREG(VCN, 0, mmUVD_STATUS, UVD_STATUS__IDLE, 0x7, r); ^ ../drivers/gpu/drm/amd/amdgpu/../amdgpu/soc15_common.h:55:10: note: expanded from macro 'SOC15_WAIT_ON_RREG' while ((tmp_ & (mask)) != (expected_value)) { \ ^ ../drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1072:7: note: initialize the variable 'r' to silence this warning int r; ^ = 0 1 warning generated.
To prevent warnings like this from happening in the future, make the SOC15_WAIT_ON_RREG macro initialize its ret variable before the while loop that can time out. This macro's return value is always checked so it should set ret in both the success and fail path.
Link: https://github.com/ClangBuiltLinux/linux/issues/776 Signed-off-by: Nathan Chancellor natechancellor@gmail.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/amd/amdgpu/soc15_common.h | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/soc15_common.h b/drivers/gpu/drm/amd/amdgpu/soc15_common.h index 0942f492d2e19..9d444f7fdfcdd 100644 --- a/drivers/gpu/drm/amd/amdgpu/soc15_common.h +++ b/drivers/gpu/drm/amd/amdgpu/soc15_common.h @@ -51,6 +51,7 @@ do { \ uint32_t tmp_ = RREG32(adev->reg_offset[ip##_HWIP][inst][reg##_BASE_IDX] + reg); \ uint32_t loop = adev->usec_timeout; \ + ret = 0; \ while ((tmp_ & (mask)) != (expected_value)) { \ udelay(2); \ tmp_ = RREG32(adev->reg_offset[ip##_HWIP][inst][reg##_BASE_IDX] + reg); \