Re: [PATCH v2 2/7] drm/panfrost: Prevent division by 0

[Boris Brezillon]

On Thu, 04 Jun 2026 18:35:21 +0100
Adrián Larumbe <adrian.larumbe@xxxxxxxxxxxxx> wrote:

> When updating and debug-printing devfreq stats, in the very unlikely
> offchance that total device time is less than 100 ns, clamp it to 0 to
> avoid division by 0.
> 
> Reported-by: Claude <noreply@xxxxxxxxxxxxx>
> Closes: https://gitlab.freedesktop.org/panfrost/linux/-/work_items/88
> Signed-off-by: Adrián Larumbe <adrian.larumbe@xxxxxxxxxxxxx>
> Fixes: f3ba91228e8e ("drm/panfrost: Add initial panfrost driver")
> ---
>  drivers/gpu/drm/panfrost/panfrost_devfreq.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> index b51c30778811..e34de47bf43b 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> @@ -78,7 +78,8 @@ static int panfrost_devfreq_get_dev_status(struct device *dev,
>  
>  	dev_dbg(pfdev->base.dev, "busy %lu total %lu %lu %% freq %lu MHz\n",
>  		status->busy_time, status->total_time,
> -		status->busy_time / (status->total_time / 100),
> +		status->total_time >= 100 ?
> +			status->busy_time / (status->total_time / 100) : 0,

or:

		status->busy_time * 100 / MAX(status->total_time, 1),

>  		status->current_frequency / 1000 / 1000);
>  
>  	return 0;
>