Re: [PATCH v3 05/11] thermal: armada: Add support for Armada AP806

Miquel RAYNAL
2017-12-18T12:25:00Z

Hi Baruch,

On Mon, 18 Dec 2017 13:11:56 +0200
Baruch Siach <baruch@tkos.co.il> wrote:

> Hi Miquèl,
>
> On Mon, Dec 18, 2017 at 10:41:27AM +0100, Miquel RAYNAL wrote:
> > Hello Gregory & Baruch,
> >
> > On Thu, 14 Dec 2017 12:05:43 +0100
> > Gregory CLEMENT <gregory.clement@free-electrons.com> wrote:
> >
> > > > @@ -184,9 +214,9 @@ static int armada_get_temp(struct
> > > > thermal_zone_device *thermal, div = priv->data->coef_div;
> > > >
> > > > if (priv->data->inverted)
> > > > - *temp = ((m * reg) - b) / div;
> > > > + *temp = ((m * sample) - b) / div;
> > > > else
> > > > - *temp = (b - (m * reg)) / div;
> > > > + *temp = (b - (m * sample)) / div;
> > > > return 0;
> > > > }
> > > >
> > > > @@ -237,6 +267,19 @@ static const struct armada_thermal_data
> > > > armada380_data = { .inverted = true,
> > > > };
> > > >
> > > > +static const struct armada_thermal_data armada_ap806_data = {
> > > > + .is_valid = armada_is_valid,
> > > > + .init_sensor = armada_ap806_init_sensor,
> > > > + .is_valid_bit = BIT(16),
> > > > + .temp_shift = 0,
> > > > + .temp_mask = 0x3ff,
> > > > + .coef_b = -150000,
> > >
> > > Don't you expect any side effect by storing a negative value in a
> > > unsigned variable?
> >
> > That is a fair question, I did not spot that.
> >
> > As other values are really close to 2^32 I don't know what is the
> > best option for us in this case. Should I:
> > - don't care?
> > - use signed values? (dangerous IMHO)
> > - use a union with a signed and an unsigned value? (problem moved
> > to ->get_temp())
>
> Another option is to use s64 type.

I prefer this one!

Thank you,
Miquèl

>
> baruch
>

--
Miquel Raynal, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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