Re: [PATCH 1/2] platform/x86: dell-ddv: Add hwmon support

[Armin Wolf]

Am 06.02.23 um 17:23 schrieb Guenter Roeck:

> On Mon, Feb 06, 2023 at 03:13:25PM +0100, Hans de Goede wrote:
> > Hi Armin,
> >
> > On 2/5/23 21:54, Armin Wolf wrote:
> > > Thanks to bugreport 216655 on bugzilla triggered by the
> > > dell-smm-hwmon driver, the contents of the sensor buffers
> > > could be almost completely decoded.
> > > Add an hwmon interface for exposing the fan and thermal
> > > sensor values. Since the WMI interface can be quite slow
> > > on some machines, the sensor buffers are cached for 1 second
> > > to lessen the performance impact.
> > > The debugfs interface remains in place to aid in reverse-engineering
> > > of unknown sensor types and the thermal buffer.
> > >
> > > Tested-by: Antonín Skala <skala.antonin@xxxxxxxxx>
> > > Tested-by: Gustavo Walbon <gustavowalbon@xxxxxxxxx>
> > > Signed-off-by: Armin Wolf <W_Armin@xxxxxx>
> > This looks nice and clean to me, thank you:
> >
> > Reviewed-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> >
> > I'm going to wait a bit with merging this to see if Guenter
> > has any remarks. If there are no remarks by next Monday then
> > I'll merge this for the 6.3 merge window.
> I don't have any further remarks. I won't send an Ack, though.
> I noticed that the empty lines before return statements distract
> me sufficiently enough that I am not sure about the actual code.
>
> Guenter

I will send a 3rd revision of the patch series to remove those empty lines then.
Speaking of a 3rd revision, i noticed that jiffies are not updated during suspend,
so the sensor values might be wrong for a short time when resuming after a long time.

This can be solved by either usingktime_get_boottime_ns(), which does not stop during suspend, or by
invalidating the sensor cache upon resume. Which method should be used
in this case? Armin Wolf