Re: [PATCH] drm/stm: Avoid using val uninitialized in ltdc_set_ycbcr_config()

[yannick Fertre]

Hi Nathan,
Thenks for the patch.

Acked-by: Yannick Fertre <yannick.fertre@xxxxxxxxxxx>

Best regards

On 2/7/22 17:53, Nathan Chancellor wrote:
> Clang warns:
>
>    drivers/gpu/drm/stm/ltdc.c:625:2: warning: variable 'val' is used uninitialized whenever switch default is taken [-Wsometimes-uninitialized]
>            default:
>            ^~~~~~~
>    drivers/gpu/drm/stm/ltdc.c:635:2: note: uninitialized use occurs here
>            val |= LxPCR_YCEN;
>            ^~~
>    drivers/gpu/drm/stm/ltdc.c:600:9: note: initialize the variable 'val' to silence this warning
>            u32 val;
>                   ^
>                    = 0
>    1 warning generated.
>
> Use a return instead of break in the default case to fix the warning.
> Add an error message so that this return is not silent, which could hide
> issues in the future.
>
> Fixes: 484e72d3146b ("drm/stm: ltdc: add support of ycbcr pixel formats")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1575
> Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
> ---
>   drivers/gpu/drm/stm/ltdc.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
> index 5eeb32c9c9ce..447ddde1786c 100644
> --- a/drivers/gpu/drm/stm/ltdc.c
> +++ b/drivers/gpu/drm/stm/ltdc.c
> @@ -624,7 +624,8 @@ static inline void ltdc_set_ycbcr_config(struct drm_plane *plane, u32 drm_pix_fm
>   		break;
>   	default:
>   		/* RGB or not a YCbCr supported format */
> -		break;
> +		drm_err(plane->dev, "Unsupported pixel format: %u\n", drm_pix_fmt);
> +		return;
>   	}
>   
>   	/* Enable limited range */
>
> base-commit: 542898c5aa5c6a3179dffb1d1606884a63f75fed