Re: [PATCH] drm/amd/display: Remove pointless NULL checks in dmub_psr_copy_settings

[Nick Desaulniers]

On Mon, Mar 2, 2020 at 2:43 PM Nathan Chancellor
<natechancellor@xxxxxxxxx> wrote:
>
> Clang warns:
>
> drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dmub_psr.c:147:31: warning:
> address of 'pipe_ctx->plane_res' will always evaluate to 'true'
> [-Wpointer-bool-conversion]
>         if (!pipe_ctx || !&pipe_ctx->plane_res || !&pipe_ctx->stream_res)
>                          ~ ~~~~~~~~~~^~~~~~~~~
> drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dmub_psr.c:147:56: warning:
> address of 'pipe_ctx->stream_res' will always evaluate to 'true'
> [-Wpointer-bool-conversion]
>         if (!pipe_ctx || !&pipe_ctx->plane_res || !&pipe_ctx->stream_res)
>                                                   ~ ~~~~~~~~~~^~~~~~~~~~
> 2 warnings generated.
>
> As long as pipe_ctx is not NULL, the address of members in this struct
> cannot be NULL, which means these checks will always evaluate to false.
>
> Fixes: 4c1a1335dfe0 ("drm/amd/display: Driverside changes to support PSR in DMCUB")
> Link: https://github.com/ClangBuiltLinux/linux/issues/915
> Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx>

Indeed, they are not pointers, and no members within `struct
plane_resource` or `struct stream_resource` seem to indicate that they
are somehow invalid.  Good job sleuthing out the correct fixes by tag.
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>

> ---
>  drivers/gpu/drm/amd/display/dc/dce/dmub_psr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/dce/dmub_psr.c b/drivers/gpu/drm/amd/display/dc/dce/dmub_psr.c
> index 2c932c29f1f9..a9e1c01e9d9b 100644
> --- a/drivers/gpu/drm/amd/display/dc/dce/dmub_psr.c
> +++ b/drivers/gpu/drm/amd/display/dc/dce/dmub_psr.c
> @@ -144,7 +144,7 @@ static bool dmub_psr_copy_settings(struct dmub_psr *dmub,
>                 }
>         }
>
> -       if (!pipe_ctx || !&pipe_ctx->plane_res || !&pipe_ctx->stream_res)
> +       if (!pipe_ctx)
>                 return false;
>
>         // First, set the psr version
> --
> 2.25.1
>


-- 
Thanks,
~Nick Desaulniers