Re: [PATCH] drm: panel: himax-hx8279: avoid using an uninitialized variable

[Neil Armstrong <neil.armstrong@linaro.org>]

Hi,

On 23/04/2025 18:32, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> goa_even_valid is only initialized in one branch but not the other:
> 
> drivers/gpu/drm/panel/panel-himax-hx8279.c:838:6: error: variable 'goa_even_valid' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
>    838 |         if (num_zero == ARRAY_SIZE(desc->goa_even_timing))
>        |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/panel/panel-himax-hx8279.c:842:23: note: uninitialized use occurs here
>    842 |         if (goa_odd_valid != goa_even_valid)
>        |                              ^~~~~~~~~~~~~~
> 
> Change the initialization to set it to the value of the condition instead.
> 
> Fixes: 38d42c261389 ("drm: panel: Add driver for Himax HX8279 DDIC panels")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>   drivers/gpu/drm/panel/panel-himax-hx8279.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-himax-hx8279.c b/drivers/gpu/drm/panel/panel-himax-hx8279.c
> index b48b350b62da..4f548430654a 100644
> --- a/drivers/gpu/drm/panel/panel-himax-hx8279.c
> +++ b/drivers/gpu/drm/panel/panel-himax-hx8279.c
> @@ -835,8 +835,7 @@ static int hx8279_check_goa_config(struct hx8279 *hx, struct device *dev)
>   			num_zero++;
>   	}
>   
> -	if (num_zero == ARRAY_SIZE(desc->goa_even_timing))
> -		goa_even_valid = false;
> +	goa_even_valid = (num_zero != ARRAY_SIZE(desc->goa_even_timing));
>   
>   	/* Programming one without the other would make no sense! */
>   	if (goa_odd_valid != goa_even_valid)

Thanks, Applying https://lore.kernel.org/all/20250423-panel-himax-hx8279-fix-sometimes-uninitialized-v2-1-fc501c6558d9@kernel.org/
instead since more complete.

Neil