[PATCH 2/2] ARM: dts: bcm283x: Add critical thermal zone for GPU

[Eric Anholt]

Stefan Wahren <stefan.wahren at i2se.com> writes:

> Hi Eric,
>
>> Eric Anholt <eric at anholt.net> hat am 8. Februar 2017 um 20:50 geschrieben:
>> 
>> 
>> Stefan Wahren <stefan.wahren at i2se.com> writes:
>> 
>> > Am 08.02.2017 um 05:23 schrieb Eduardo Valentin:
>> >> On Tue, Feb 07, 2017 at 08:19:31PM -0800, Eduardo Valentin wrote:
>> >>> On Sat, Feb 04, 2017 at 02:16:27PM +0000, Stefan Wahren wrote:
>> >>>> As suggested by Eduardo Valentin this adds the thermal zone for
>> >>>> the bcm2835 SoC. Since we currently don't have any cooling devices
>> >>>> leave this section empty.
>> >>>>
>> >>>> Signed-off-by: Stefan Wahren <stefan.wahren at i2se.com>
>> >>>> ---
>> >>>>  arch/arm/boot/dts/bcm283x.dtsi |   19 +++++++++++++++++++
>> >>>>  1 file changed, 19 insertions(+)
>> >>>>
>> >>>> diff --git a/arch/arm/boot/dts/bcm283x.dtsi b/arch/arm/boot/dts/bcm283x.dtsi
>> >>>> index 9c7ec7e..359da9d 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 {
>> >>>> +		gpu_thermal: gpu-thermal {
>> >>>> +			polling-delay-passive = <0>;
>> >>>> +			polling-delay = <1000>;
>> >>>> +
>> >>>> +			thermal-sensors = <&thermal>;
>> >> Just came to my mind, dont you need to have an id to specify with sensor
>> >> points to gpu?
>> >
>> > Sorry, i don't know the exact setup of the single thermal sensor on the
>> > SoC (datasheet doesn't provide any helpful information). I adapted the
>> > Renesas R-Car thermal binding because i think it would be the best match.
>> >
>> > @Eric: What's your opinion?
>> 
>> I don't understand the question.
>
> i hope to get it right. We are talking about defining the thermal zone [1].
>
> There are 4 examples:
>
> (a) - CPU thermal zone with one internal sensor
> (b) - IC with several internal sensors
> (c) - Several sensors within one single thermal zone
> (d) - Board thermal
>
> I decided to choose (a) for the patch and Eduardo tends to (b).
>
> Here are the questions:
>
> Where is the thermal sensor TSENS located (ARM core or VideoCore 4)?
>
> Do we expect several internal sensors?

There is only one temperature sensor on the chip, and no others on the
board that I know of.  The docs for tsens don't say if the actual sensor
is closer to the center of the ARM or some VC4 component within the
chip.
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