Re: [PATCH V2 2/2] ARM: dts: bcm283x: Add CPU thermal zone with 1 trip point

[Stefan Wahren <stefan.wahren@i2se.com>]

> Eduardo Valentin <edubezval@gmail.com> hat am 19. Februar 2017 um 22:27 geschrieben:
> 
> 
> Hey Stefan,
> 
> 
> On Sun, Feb 19, 2017 at 01:31:49PM +0100, Stefan Wahren wrote:
> > Hi Eduardo,
> > 
> > > Eduardo Valentin <edubezval@gmail.com> hat am 19. Februar 2017 um 02:17 geschrieben:
> > > 
> > > 
> > > On Sun, Feb 12, 2017 at 07:38:48PM +0000, Stefan Wahren wrote:
> > > > As suggested by Eduardo Valentin this adds the thermal zone for
> > > > the bcm2835 SoC with its single thermal sensor. We start with
> > > > the criticial trip point and leave the cooling devices empty
> > > > since we don't have any at the moment.
> > > > 
> > > > Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
> > > > ---
> > > > 
> > > > Changes in V2:
> > > > - add missing thermal-sensor-cells property
> > > > - change gpu-thermal to cpu-thermal
> > > > 
> > > >  arch/arm/boot/dts/bcm283x.dtsi |   20 ++++++++++++++++++++
> > > >  1 file changed, 20 insertions(+)
> > > > 
> > > > diff --git a/arch/arm/boot/dts/bcm283x.dtsi b/arch/arm/boot/dts/bcm283x.dtsi
> > > > index a3106aa..4dc74f6 100644
> > > > --- a/arch/arm/boot/dts/bcm283x.dtsi
> > > > +++ b/arch/arm/boot/dts/bcm283x.dtsi
> > > > @@ -19,6 +19,25 @@
> > > >  		bootargs = "earlyprintk console=ttyAMA0";
> > > >  	};
> > > >  
> > > > +	thermal-zones {
> > > > +		cpu_thermal: cpu-thermal {
> > > > +			polling-delay-passive = <0>;
> > > > +			polling-delay = <1000>;
> > > > +
> > > 
> > > Check the diff I sent and also add the following for differentiating the
> > > offsets and slopes depending on which chip the zone describes:
> > > 			coefficients = <-538 407000>; /* for the zone on bcm2835 and bcm2836 */
> > > 
> > > and
> > > 
> > > 			coefficients = <-538 412000>; /* for the zone on bcm2837 */
> > > 
> > > 
> > > Despite the changes mentioned for the driver and DT, I am ok with the driver and the DTS descriptors.
> > 
> > thanks for providing the necessary driver changes, but the coefficients above causes a DTC parse error. The Device Tree doesn't provide support for native signed integer. Looking at this old thread [1] suggests to add parentheses which fixed the parse issue. But of-thermal expected u32 for coefficients [2].
> > 
> > Any suggestions?
> 
> I am OK if you provide a patch to of-thermal in your series, assuming
> that would fix the  representation issue the data of your driver has.
> 

I prepared a new patch series to fix that issue in my github repo [1]. At first we need to implement a new function of_property_read_s32_array() [2]. After that we could use this function in of-thermal in order to use signed integer for both coefficients [3].

@Eduardo: Is it okay for you?

@Martin: Do you want to send the next version of the patch series or should i?

[1] - https://github.com/lategoodbye/rpi-zero/commits/thermal
[2] - https://github.com/lategoodbye/rpi-zero/commit/3dc43581ada74d1345f79b4c36562fdf5f7941e5
[3] - https://github.com/lategoodbye/rpi-zero/commit/c02ed37c0ebdca98aee570862af10e90b3c9a0d0

> BR,
> 
> > 
> > [1] - http://lists.infradead.org/pipermail/linux-arm-kernel/2013-April/159681.html
> > [2] - http://elixir.free-electrons.com/source/drivers/thermal/of-thermal.c?v=4.10-rc7#L854
> > 
> > > 
> > > BR,