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drm/amdgpu: Ensure ret is always initialized when using SOC15_WAIT_ON_RREG 

Commit b0f3cd3191 ("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>
This commit is contained in:
Nathan Chancellor 2019-11-23 12:23:36 -07:00 committed by Alex Deucher
parent 07863a6cc2
commit a63141e317
1 changed files with 1 additions and 0 deletions
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1
drivers/gpu/drm/amd/amdgpu/soc15_common.h
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@ -52,6 +52,7 @@
uint32_t old_ = 0; \
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)) { \
if (old_ != tmp_) { \
loop = adev->usec_timeout; \