Re: [PATCH v2 4/9] of: Add bindings of hw throttle for soctherm

[Wei Ni]

On 2016å04æ28æ 22:48, Eduardo Valentin wrote:
> On Thu, Apr 28, 2016 at 02:48:41PM +0800, Wei Ni wrote:
>>
>>
>> On 2016å04æ28æ 07:30, Eduardo Valentin wrote:
>>> From: Eduardo Valentin <edubezval@xxxxxxxxx>
>>> To: Wei Ni <wni@xxxxxxxxxx>
>>> Cc: thierry.reding@xxxxxxxxx, robh+dt@xxxxxxxxxx, rui.zhang@xxxxxxxxx,
>>> 	MLongnecker@xxxxxxxxxx, swarren@xxxxxxxxxxxxx,
>>> 	mikko.perttunen@xxxxxxxx, linux-tegra@xxxxxxxxxxxxxxx,
>>> 	linux-pm@xxxxxxxxxxxxxxx, devicetree@xxxxxxxxxxxxxxx,
>>> 	linux-kernel@xxxxxxxxxxxxxxx
>>> Bcc: 
>>> Subject: Re: [PATCH v2 4/9] of: Add bindings of hw throttle for soctherm
>>> Reply-To: 
>>> In-Reply-To: <1461727554-15065-5-git-send-email-wni@xxxxxxxxxx>
>>>
>>> The patch title must say something about the fact that this is specific
>>> to nvidia thermal driver.
>>
>> Yes, it's my mistake, will fix it in next series.
>>
>>>
>>> On Wed, Apr 27, 2016 at 11:25:49AM +0800, Wei Ni wrote:
>>>> Add HW throttle configuration sub-node for soctherm, which
>>>> is used to describe the throttle event, and worked as a
>>>> cooling device. The "hot" type trip in thermal zone can
>>>> be bound to this cooling device, and trigger the throttle
>>>> function.
>>>>
>>>> Signed-off-by: Wei Ni <wni@xxxxxxxxxx>
>>>> ---
>>>>  .../bindings/thermal/nvidia,tegra124-soctherm.txt  | 89 +++++++++++++++++++++-
>>>>  1 file changed, 87 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/thermal/nvidia,tegra124-soctherm.txt b/Documentation/devicetree/bindings/thermal/nvidia,tegra124-soctherm.txt
>>>> index edebfa0a985e..dc337d139f49 100644
>>>> --- a/Documentation/devicetree/bindings/thermal/nvidia,tegra124-soctherm.txt
>>>> +++ b/Documentation/devicetree/bindings/thermal/nvidia,tegra124-soctherm.txt
>>>> @@ -10,8 +10,14 @@ Required properties :
>>>>  - compatible : For Tegra124, must contain "nvidia,tegra124-soctherm".
>>>>    For Tegra132, must contain "nvidia,tegra132-soctherm".
>>>>    For Tegra210, must contain "nvidia,tegra210-soctherm".
>>>> -- reg : Should contain 1 entry:
>>>> +- reg : Should contain at least 2 entries for each entry in reg-names:
>>>>    - SOCTHERM register set
>>>> +  - Tegra CAR register set: Required for Tegra124 and Tegra210.
>>>> +  - CCROC register set: Required for Tegra132.
>>>> +- reg-names :  Should contain at least 2 entries:
>>>> +  - soctherm-reg
>>>> +  - car-reg
>>>> +  - ccroc-reg
>>>>  - interrupts : Defines the interrupt used by SOCTHERM
>>>>  - clocks : Must contain an entry for each entry in clock-names.
>>>>    See ../clocks/clock-bindings.txt for details.
>>>> @@ -25,17 +31,44 @@ Required properties :
>>>>  - #thermal-sensor-cells : Should be 1. See ./thermal.txt for a description
>>>>      of this property. See <dt-bindings/thermal/tegra124-soctherm.h> for a
>>>>      list of valid values when referring to thermal sensors.
>>>> +- throttle-cfgs: A sub-node which is a container of configuration for each
>>>> +    hardware throttle events. These events can be set as cooling devices.
>>>> +  * throttle events: Sub-nodes must be named as "light" or "heavy".
>>>> +      Properties:
>>>> +      - priority: Each throttles has its own throttle settings, so the SW need
>>>> +        to set priorities for various throttle, the HW arbiter can select the
>>>> +        final throttle settings.
>>>> +        Bigger value indicates higher priority, In general, higher priority
>>>> +        translates to lower target frequency. SW needs to ensure that critical
>>>> +        thermal alarms are given higher priority, and ensure that there is
>>>> +        no race if priority of two vectors is set to the same value.
>>>> +      - cpu-throt-depth:  This property is for Tegra124 and Tegra210. It is
>>>> +        the throttling depth of pulse skippers, it's the percentage
>>>> +        throttling.
>>>> +      - cpu-throt-level: This property is only for Tegra132, it is the level
>>>> +        of pulse skippers, which used to throttle clock frequencies. It
>>>> +        indicates cpu clock throttling depth, and the depth can be programmed.
>>>> +        Must set as following values:
>>>> +        TEGRA_SOCTHERM_THROT_LEVEL_LOW, TEGRA_SOCTHERM_THROT_LEVEL_MED
>>>> +        TEGRA_SOCTHERM_THROT_LEVEL_HIGH, TEGRA_SOCTHERM_THROT_LEVEL_NONE
>>>
>>> These properties are not generic properties. My understanding is that
>>> you must have vendor prefix in such case. Same applies to the new nodes.
>>
>> Ok, will do it.
>>
>>>
>>>> +      - #cooling-cells: Should be 1. This cooling device only support on/off state.
>>>> +        See ./thermal.txt for a description of this property.
>>>>  
>>>>  Note:
>>>>  - the "critical" type trip points will be set to SOC_THERM hardware as the
>>>>  shut down temperature. Once the temperature of this thermal zone is higher
>>>>  than it, the system will be shutdown or reset by hardware.
>>>> +- the "hot" type trip points will be set to SOC_THERM hardware as the throttle
>>>> +temperature. Once the the temperature of this thermal zone is higher
>>>> +than it, it will trigger the HW throttle event.
>>>>  
>>>>  Example :
>>>>  
>>>>  	soctherm@700e2000 {
>>>>  		compatible = "nvidia,tegra124-soctherm";
>>>> -		reg = <0x0 0x700e2000 0x0 0x1000>;
>>>> +		reg = <0x0 0x700e2000 0x0 0x600  /* SOC_THERM reg_base */
>>>> +			0x0 0x60006000 0x0 0x400 /* CAR reg_base */
>>>> +		reg-names = "soctherm-reg", "car-reg";
>>>>  		interrupts = <GIC_SPI 48 IRQ_TYPE_LEVEL_HIGH>;
>>>>  		clocks = <&tegra_car TEGRA124_CLK_TSENSOR>,
>>>>  			<&tegra_car TEGRA124_CLK_SOC_THERM>;
>>>> @@ -44,6 +77,45 @@ Example :
>>>>  		reset-names = "soctherm";
>>>>  
>>>>  		#thermal-sensor-cells = <1>;
>>>> +
>>>> +		throttle-cfgs {
>>>> +			throttle_heavy: heavy {
>>>> +				priority = <100>;
>>>> +				cpu-throt-depth = <85>;
>>>> +
>>>> +				#cooling-cells = <1>;
>>>> +			};
>>>> +			throttle_light: light {
>>>> +				priority = <80>;
>>>> +				cpu-throt-depth = <50>;
>>>> +
>>>> +				#cooling-cells = <1>;
>>>> +			};
>>>> +		};
>>>
>>> This is a sensor, which at the same time, has sub nodes that can be
>>> cooling devices. Is my understanding correct of what you are trying to
>>> do?
>>
>> Yes, we set this sub nodes as cooling devices.
>> Let me explain it.
>> The Tegra's soctherm has the HW throttle function, it will be triggered when the
>> temperatures reach to the "hot" type trip. These throttle events can be
>> configured to different levels "heavy" and "light" on different sensors. So it
>> something like cooling devices which can be bound with thermal zones, and in
>> this way, we can use the linux of-thermal framework to handle it. If not, we
>> have to add more codes to parse these configuration and set them for those
>> sensors. I had used this method to handle the shutdown function in Tegra's
>> soctherm driver in my previous series, however Rob didn't like it, he preferred
>> to use linux framework to handle it.
>> So I think it's better to set these throttle-cfgs as cooling devices, so they
>> can be bound to the cpu/gpu thermal zones easily.
>>
>>>
>>>
>>>> +	};
>>>> +
>>>> +Example: referring to Tegra132's "reg", "reg-names" and "throttle-cfgs" :
>>>> +
>>>> +	soctherm@0,700e2000 {
>>>> +		compatible = "nvidia,tegra132-soctherm";
>>>> +		reg = <0x0 0x700e2000 0x0 0x600  /* SOC_THERM reg_base */
>>>> +			0x0 0x70040000 0x0 0x200>; /* CCROC reg_base */;
>>>> +		reg-names = "soctherm-reg", "ccroc-reg";
>>>> +
>>>> +		throttle-cfgs {
>>>> +			throttle_heavy: heavy {
>>>> +				priority = <100>;
>>>> +				cpu-throt-level = <TEGRA_SOCTHERM_THROT_LEVEL_HIGH>;
>>>> +
>>>> +				#cooling-cells = <1>;
>>>> +			};
>>>> +			throttle_light: light {
>>>> +				priority = <80>;
>>>> +				cpu-throt-level = <TEGRA_SOCTHERM_THROT_LEVEL_MED>;
>>>> +
>>>> +				#cooling-cells = <1>;
>>>
>>> Could you please describe a little here what to expect of the above
>>> setup?
>>
>> Ok, let me describe it.
>> When the "heavy" cooling device triggered, the hardware will skip cpu clock's
>> pulse in HIGH level, and if the "light" triggered, the hardware will skip cpu
>> clock's pulse in MED level.
>> If these two devices are triggered in same time, the HW throttle arbiter will
>> select the highest priority as the final throttle settings to skip cpu pulse.
> 
> 
> I would prefer if you add these descriptions into your examples in your
> next version.

Sure, will do it.

>