2021-09-30 16:19:43

by Nathan Chancellor

Subject: [PATCH] drm/amd: Initialize remove_mpcc in dcn201_update_mpcc()

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 <[email protected]>
---
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

2021-09-30 19:00:06

by Alex Deucher

Subject: Re: [PATCH] drm/amd: Initialize remove_mpcc in dcn201_update_mpcc()

Applied. Thanks!

Alex

On Thu, Sep 30, 2021 at 12:16 PM Nathan Chancellor <[email protected]> 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 <[email protected]>
> ---
> 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
>