Re: [PATCH] drm/msm/dpu: Initialize crtc_state to NULL in dpu_plane_virtual_atomic_check()

[Jessica Zhang <jessica.zhang@oss.qualcomm.com>]

On 7/15/2025 4:27 PM, Nathan Chancellor wrote:
> After a recent change in clang to expose uninitialized warnings from
> const variables and pointers [1], there is a warning around crtc_state
> in dpu_plane_virtual_atomic_check():
> 
>    drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c:1145:6: error: variable 'crtc_state' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
>     1145 |         if (plane_state->crtc)
>          |             ^~~~~~~~~~~~~~~~~
>    drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c:1149:58: note: uninitialized use occurs here
>     1149 |         ret = dpu_plane_atomic_check_nosspp(plane, plane_state, crtc_state);
>          |                                                                 ^~~~~~~~~~
>    drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c:1145:2: note: remove the 'if' if its condition is always true
>     1145 |         if (plane_state->crtc)
>          |         ^~~~~~~~~~~~~~~~~~~~~~
>     1146 |                 crtc_state = drm_atomic_get_new_crtc_state(state,
>    drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c:1139:35: note: initialize the variable 'crtc_state' to silence this warning
>     1139 |         struct drm_crtc_state *crtc_state;
>          |                                          ^
>          |                                           = NULL
> 
> Initialize crtc_state to NULL like other places in the driver do, so
> that it is consistently initialized.
> 
> Cc: stable@vger.kernel.org
> Closes: https://github.com/ClangBuiltLinux/linux/issues/2106
> Fixes: 774bcfb73176 ("drm/msm/dpu: add support for virtual planes")
> Link: https://github.com/llvm/llvm-project/commit/2464313eef01c5b1edf0eccf57a32cdee01472c7 [1]
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Reviewed-by: Jessica Zhang <jessica.zhang@oss.qualcomm.com>

> ---
>   drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> index 421138bc3cb7..30ff21c01a36 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> @@ -1136,7 +1136,7 @@ static int dpu_plane_virtual_atomic_check(struct drm_plane *plane,
>   	struct drm_plane_state *old_plane_state =
>   		drm_atomic_get_old_plane_state(state, plane);
>   	struct dpu_plane_state *pstate = to_dpu_plane_state(plane_state);
> -	struct drm_crtc_state *crtc_state;
> +	struct drm_crtc_state *crtc_state = NULL;
>   	int ret;
>   
>   	if (IS_ERR(plane_state))
> 
> ---
> base-commit: d3deabe4c619875714b9a844b1a3d9752dbae1dd
> change-id: 20250715-drm-msm-fix-const-uninit-warning-2b93cef9f1c6
> 
> Best regards,
> --
> Nathan Chancellor <nathan@kernel.org>
>