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drm/amd/powerplay: Zero initialize num_of_levels in vega20_set_single_dpm_table

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When building with -Wsometimes-uninitialized, Clang warns:

drivers/gpu/drm/amd/amdgpu/../powerplay/vega20_ppt.c:456:2: warning:
variable 'num_of_levels' is used uninitialized whenever '?:' condition
is false [-Wsometimes-uninitialized]
        smu_read_smc_arg(smu, &num_of_levels);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/../powerplay/inc/amdgpu_smu.h:608:3: note:
expanded from macro 'smu_read_smc_arg'
        ((smu)->funcs->read_smc_arg? (smu)->funcs->read_smc_arg((smu), (arg)) : 0)
         ^~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/../powerplay/vega20_ppt.c:457:7: note:
uninitialized use occurs here
        if (!num_of_levels) {
             ^~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/../powerplay/vega20_ppt.c:456:2: note: remove
the '?:' if its condition is always true
        smu_read_smc_arg(smu, &num_of_levels);
        ^
drivers/gpu/drm/amd/amdgpu/../powerplay/inc/amdgpu_smu.h:608:3: note:
expanded from macro 'smu_read_smc_arg'
        ((smu)->funcs->read_smc_arg? (smu)->funcs->read_smc_arg((smu), (arg)) : 0)
         ^
drivers/gpu/drm/amd/amdgpu/../powerplay/vega20_ppt.c:446:27: note:
initialize the variable 'num_of_levels' to silence this warning
        uint32_t i, num_of_levels, clk;
                                 ^
                                  = 0
1 warning generated.

The if statement it mentions as potentially problematic is currently
always true because the read_smc_arg callback is assigned at the
bottom of this file but Clang can't tell that. If the callback were
ever to disappear, num_of_levels would never be initialized. Just
zero initialize it to ensure that the intent behind this code
remains the same.

Link: https://github.com/ClangBuiltLinux/linux/issues/425
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Nathan Chancellor 2019-03-19 17:58:42 -07:00 committed by Alex Deucher
parent 5bbfcebb6d
commit 5ea8b4725f
1 changed files with 1 additions and 1 deletions
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2
drivers/gpu/drm/amd/powerplay/vega20_ppt.c
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@ -443,7 +443,7 @@ vega20_set_single_dpm_table(struct smu_context *smu,
PPCLK_e clk_id)
{
int ret = 0;
uint32_t i, num_of_levels, clk;
uint32_t i, num_of_levels = 0, clk;
ret = smu_send_smc_msg_with_param(smu,
SMU_MSG_GetDpmFreqByIndex,