linux-kernel - Re: [PATCH V4 07/11] of: Add bindings of hw-trip-points for soctherm

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Date:	Tue, 26 Jan 2016 14:11:01 +0800
From:	Wei Ni <wni@...dia.com>
To:	Rob Herring <robh@...nel.org>
CC:	<thierry.reding@...il.com>, <rui.zhang@...el.com>,
	<MLongnecker@...dia.com>, <swarren@...dotorg.org>,
	<mikko.perttunen@...si.fi>, <linux-tegra@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>
Subject: Re: [PATCH V4 07/11] of: Add bindings of hw-trip-points for soctherm



On 2016年01月26日 10:41, Rob Herring wrote:
> On Mon, Jan 25, 2016 at 06:46:36PM +0800, Wei Ni wrote:
>> Add hw-trips sub-node for soctherm, which is
>> used to describe the hardware trip points for
>> each soctherm sensors.
> 
> This seems like something that should be common. There was a hwmon 
> binding just the other day with temperature set points.

I have checked the thermal_hwmon.c, but we can't use it. Because we use
of-thermal to register thermal zone, but it doesn't support to register to
hwmon. And it only support to show the critical temperature.
I think this sub-node is used for Tegra's soctherm specifically. And it's not
only for shutdown/reset, it also will be used to describe the hw-throttle
function in next serial patches (I'm preparing it, didn't send out yet).

BTW, I didn't find the hwmon binding to introduce the hw trips in TOT
kernel-next, could you show me it?

> 
>> Signed-off-by: Wei Ni <wni@...dia.com>
>> ---
>>  .../devicetree/bindings/thermal/tegra-soctherm.txt | 24 ++++++++++++++++++++++
>>  1 file changed, 24 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/thermal/tegra-soctherm.txt b/Documentation/devicetree/bindings/thermal/tegra-soctherm.txt
>> index 6b68cd150405..75dc9dbe7e1a 100644
>> --- a/Documentation/devicetree/bindings/thermal/tegra-soctherm.txt
>> +++ b/Documentation/devicetree/bindings/thermal/tegra-soctherm.txt
>> @@ -26,6 +26,15 @@ Required properties :
>>      of this property. See <dt-bindings/thermal/tegra124-soctherm.h> for a
>>      list of valid values when referring to thermal sensors.
>>  
>> +Optional properties:
>> +- hw-trip-points : A sub-node which is a container of hardware trip points
>> +    for each sensors.
>> +  * sensors: Sub-nodes which are used to describe the HW trip points info,
>> +        must be named as "cpu", "gpu", "mem", "pll".
>> +      Properties:
>> +      - thermtrip-temperature : Shutdown or reset temperature in millicelsius,
>> +        once the temperature of this sensor is higher than the
>> +        thermtrip-temperature, the system will be shutdown or reset.
> 
> Append units and temperature is a bit redundant. Something like 
> thermtrip-mC or thermtrip-milliC

Hmm, got it, will change it in next version.

> 
> You could easily have multiple levels of trip points, so perhaps the 
> name needs to reflect the action (i.e. shutdown).

This temperature can trigger shutdown or reset, it depends on the platform
design, and the Tegra's SPEC call it as thermtrip, so I use this name. I prefer
to use "thermtgrip-mC".

> 
> Rob
>