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

[Steven Price]

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:

Reviewed-by: Steven Price <steven.price@xxxxxxx>

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