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

[Adrián Larumbe]

On 05.06.2026 11:29, Steven Price wrote:
> On 04/06/2026 19:02, Boris Brezillon wrote:
> > 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),
> > 
> 
> I have to admit I prefer Boris' version ;)
> 
> But either way:

Me too, I'm picking it for the next revision.

> Reviewed-by: Steven Price <steven.price@xxxxxxx>
> 
> >>  		status->current_frequency / 1000 / 1000);
> >>  
> >>  	return 0;
> >>
> > 

Adrian Larumbe