Re: [PATCH v6] drm/i915/hwmon: expose fan speed

Andy Shevchenko
2024-08-20T10:23:42Z

On Tue, Aug 20, 2024 at 11:50:10AM +0530, Raag Jadav wrote:
> Add hwmon support for fan1_input attribute, which will expose fan speed
> in RPM. With this in place we can monitor fan speed using lm-sensors tool.
>
> $ sensors
> i915-pci-0300
> Adapter: PCI adapter
> in0: 653.00 mV
> fan1: 3833 RPM
> power1: N/A (max = 43.00 W)
> energy1: 32.02 kJ

> v2: Handle overflow, add mutex protection and ABI documentation
> Aesthetic adjustments (Riana)
> v3: Change rotations data type, ABI date and version
> v4: Fix wakeref leak
> Drop switch case and simplify hwm_fan_xx() (Andi)
> v5: Rework time calculation, aesthetic adjustments (Andy)
> v6: Drop overflow logic (Andy)
> Aesthetic adjustments (Badal)

But it still has an issue with 64-bit division on 32-bit platforms, right?

...

> + /*
> + * Calculate fan speed in RPM by time averaging two subsequent
> + * readings in minutes.
> + * RPM = number of rotations * msecs per minute / time in msecs
> + */
> + *val = DIV_ROUND_UP(rotations * (MSEC_PER_SEC * 60), time);

...somewhere here?

--
With Best Regards,
Andy Shevchenko