linux-kernel - Re: [PATCH] drm/stm: Avoid using val uninitialized in ltdc_set_ycbcr

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Date:   Tue, 8 Feb 2022 09:52:32 +0100
From:   Raphael Gallais-Pou <raphael.gallais-pou@...s.st.com>
To:     Nathan Chancellor <nathan@...nel.org>,
        Yannick Fertre <yannick.fertre@...s.st.com>,
        Philippe Cornu <philippe.cornu@...s.st.com>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>
CC:     <llvm@...ts.linux.dev>, Nick Desaulniers <ndesaulniers@...gle.com>,
        <linux-kernel@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] drm/stm: Avoid using val uninitialized in
 ltdc_set_ycbcr_config()

Hello Nathan,


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@...nel.org>
> ---
>  drivers/gpu/drm/stm/ltdc.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)


Reviewed-by: Raphael Gallais-Pou <raphael.gallais-pou@...s.st.com>


Thanks,

Raphaël