Re: [PATCH 2/2] drm/msm/dsi: fix 32-bit signed integer extension in pclk_rate calculation

[Dmitry Baryshkov]

On Sat, Oct 05, 2024 at 10:38:10AM GMT, Jonathan Marek wrote:
> When (mode->clock * 1000) is larger than (1<<31), int to unsigned long
> conversion will sign extend the int to 64 bits and the pclk_rate value
> will be incorrect.
> 
> Fix this by making the result of the multiplication unsigned.
> 
> Note that above (1<<32) would still be broken and require more changes, but
> its unlikely anyone will need that anytime soon.
> 

Fixes?

> Signed-off-by: Jonathan Marek <jonathan@xxxxxxxx>
> ---
>  drivers/gpu/drm/msm/dsi/dsi_host.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> index 1205aa398e445..a98d24b7cb00b 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> @@ -550,7 +550,7 @@ static unsigned long dsi_get_pclk_rate(const struct drm_display_mode *mode,
>  {
>  	unsigned long pclk_rate;
>  
> -	pclk_rate = mode->clock * 1000;
> +	pclk_rate = mode->clock * 1000u;
>  
>  	if (dsc)
>  		pclk_rate = dsi_adjust_pclk_for_compression(mode, dsc);
> -- 
> 2.45.1
> 

-- 
With best wishes
Dmitry