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Message-ID: <5722F73A.7020606@nvidia.com>
Date: Fri, 29 Apr 2016 13:55:06 +0800
From: Wei Ni <wni@...dia.com>
To: Eduardo Valentin <edubezval@...il.com>
CC: <thierry.reding@...il.com>, <robh+dt@...nel.org>,
<rui.zhang@...el.com>, <MLongnecker@...dia.com>,
<swarren@...dotorg.org>, <mikko.perttunen@...si.fi>,
<linux-tegra@...r.kernel.org>, <linux-pm@...r.kernel.org>,
<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 4/9] of: Add bindings of hw throttle for soctherm
On 2016年04月28日 22:48, Eduardo Valentin wrote:
> On Thu, Apr 28, 2016 at 02:48:41PM +0800, Wei Ni wrote:
>>
>>
>> On 2016年04月28日 07:30, Eduardo Valentin wrote:
>>> From: Eduardo Valentin <edubezval@...il.com>
>>> To: Wei Ni <wni@...dia.com>
>>> Cc: thierry.reding@...il.com, robh+dt@...nel.org, rui.zhang@...el.com,
>>> MLongnecker@...dia.com, swarren@...dotorg.org,
>>> mikko.perttunen@...si.fi, linux-tegra@...r.kernel.org,
>>> linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
>>> linux-kernel@...r.kernel.org
>>> 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@...dia.com>
>>>
>>> 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@...dia.com>
>>>> ---
>>>> .../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@...e2000 {
>>>> 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.
>
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