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List:       dri-devel
Subject:    Re: [PATCH] drm/amd: Initialize remove_mpcc in dcn201_update_mpcc()
From:       Alex Deucher <alexdeucher () gmail ! com>
Date:       2021-09-30 17:18:44
Message-ID: CADnq5_PS3T6GpqL0zi6ct+QFFzutPJEuTy638O=-ik=LETKMYQ () mail ! gmail ! com
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Applied.  Thanks!

Alex

On Thu, Sep 30, 2021 at 12:16 PM Nathan Chancellor <nathan@kernel.org> wrote:
> 
> Clang warns:
> 
> drivers/gpu/drm/amd/amdgpu/../display/dc/dcn201/dcn201_hwseq.c:505:6: error: \
> variable 'remove_mpcc' is used uninitialized whenever 'if' condition is false \
> [-Werror,-Wsometimes-uninitialized] if \
> (mpc->funcs->get_mpcc_for_dpp_from_secondary) \
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ \
> drivers/gpu/drm/amd/amdgpu/../display/dc/dcn201/dcn201_hwseq.c:509:6: note: \
> uninitialized use occurs here if (remove_mpcc != NULL && \
> mpc->funcs->remove_mpcc_from_secondary) ^~~~~~~~~~~
> drivers/gpu/drm/amd/amdgpu/../display/dc/dcn201/dcn201_hwseq.c:505:2: note: remove \
> the 'if' if its condition is always true if \
> (mpc->funcs->get_mpcc_for_dpp_from_secondary) \
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ \
> drivers/gpu/drm/amd/amdgpu/../display/dc/dcn201/dcn201_hwseq.c:442:26: note: \
> initialize the variable 'remove_mpcc' to silence this warning struct mpcc \
> *remove_mpcc; ^
> = NULL
> 1 error generated.
> 
> The code already handles remove_mpcc being NULL just fine so initialize
> it to NULL at the beginning of the function so it is never used
> uninitialized.
> 
> Fixes: ff7e396f822f ("drm/amd/display: add cyan_skillfish display support")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1469
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
> drivers/gpu/drm/amd/display/dc/dcn201/dcn201_hwseq.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/dc/dcn201/dcn201_hwseq.c \
> b/drivers/gpu/drm/amd/display/dc/dcn201/dcn201_hwseq.c index \
>                 ceaaeeb8f2de..cfd09b3f705e 100644
> --- a/drivers/gpu/drm/amd/display/dc/dcn201/dcn201_hwseq.c
> +++ b/drivers/gpu/drm/amd/display/dc/dcn201/dcn201_hwseq.c
> @@ -439,7 +439,7 @@ void dcn201_update_mpcc(struct dc *dc, struct pipe_ctx \
> *pipe_ctx) bool per_pixel_alpha = pipe_ctx->plane_state->per_pixel_alpha && \
> pipe_ctx->bottom_pipe; int mpcc_id, dpp_id;
> struct mpcc *new_mpcc;
> -       struct mpcc *remove_mpcc;
> +       struct mpcc *remove_mpcc = NULL;
> struct mpc *mpc = dc->res_pool->mpc;
> struct mpc_tree *mpc_tree_params = &(pipe_ctx->stream_res.opp->mpc_tree_params);
> 
> 
> base-commit: 30fc33064c846df29888c3c61e30a064aad3a342
> --
> 2.33.0.591.gddb1055343
> 


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