linux-kernel - Re: [PATCH v13 4/5] ARM: dts: add main Thermal info to rk3288

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Message-ID: <E4EEE800-5701-45E5-9E97-D3B036DC2F17@gmail.com>
Date:	Thu, 23 Oct 2014 18:37:55 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Caesar Wang <caesar.wang@...k-chips.com>
CC:	heiko@...ech.de, rui.zhang@...el.com, edubezval@...il.com,
	zyf@...k-chips.com, dianders@...omium.org,
	linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	devicetree@...r.kernel.org, linux-doc@...r.kernel.org,
	cf@...k-chips.com, dbasehore@...omium.org, huangtao@...k-chips.com,
	cjf@...k-chips.com, zhengsq@...k-chips.com
Subject: Re: [PATCH v13 4/5] ARM: dts: add main Thermal info to rk3288

On October 23, 2014 6:08:52 PM PDT, Caesar Wang <caesar.wang@...k-chips.com> wrote:
>Dmitry,
>
>在 2014/10/24 8:46, Dmitry Torokhov 写道:
>> Hi Caesar,
>>
>> On Thu, Oct 23, 2014 at 05:40:06PM +0800, Caesar Wang wrote:
>>> This patch is depend on rk3288-thermal.dtsi,or
>>> it will compile error.
>>>
>>> If the temperature over a period of time High,over 120C
>>> the resulting TSHUT gave CRU module,let it reset
>>> the entire chip,or via GPIO give PMIC.
>>>
>>> Signed-off-by: Caesar Wang <caesar.wang@...k-chips.com>
>>> ---
>>>   arch/arm/boot/dts/rk3288.dtsi | 21 +++++++++++++++++++++
>>>   1 file changed, 21 insertions(+)
>>>
>>> diff --git a/arch/arm/boot/dts/rk3288.dtsi
>b/arch/arm/boot/dts/rk3288.dtsi
>>> index cb18bb4..85fc17a 100644
>>> --- a/arch/arm/boot/dts/rk3288.dtsi
>>> +++ b/arch/arm/boot/dts/rk3288.dtsi
>>> @@ -15,6 +15,7 @@
>>>   #include <dt-bindings/interrupt-controller/arm-gic.h>
>>>   #include <dt-bindings/pinctrl/rockchip.h>
>>>   #include <dt-bindings/clock/rk3288-cru.h>
>>> +#include <dt-bindings/thermal/thermal.h>
>>>   #include "skeleton.dtsi"
>>>   
>>>   / {
>>> @@ -66,6 +67,7 @@
>>>   				 216000  900000
>>>   				 126000  900000
>>>   			>;
>>> +			#cooling-cells = <2>; /* min followed by max */
>>>   			clock-latency = <40000>;
>>>   			clocks = <&cru ARMCLK>;
>>>   		};
>>> @@ -346,6 +348,19 @@
>>>   		status = "disabled";
>>>   	};
>>>   
>>> +	tsadc: tsadc@...80000 {
>>> +		compatible = "rockchip,rk3288-tsadc";
>>> +		reg = <0xff280000 0x100>;
>>> +		interrupts = <GIC_SPI 37 IRQ_TYPE_LEVEL_HIGH>;
>>> +		clocks = <&cru SCLK_TSADC>, <&cru PCLK_TSADC>;
>>> +		clock-names = "tsadc", "apb_pclk";
>>> +		pinctrl-names = "default";
>>> +		pinctrl-0 = <&otp_out>;
>>> +		#thermal-sensor-cells = <1>;
>>> +		hw-shut-temp = <120000>;
>> I do not think this is a good value. You have (in the other DTS file)
>> passive trip point at 80 and critical (which should result in orderly
>> shutdown) at 125. But here you define hardware-controlled shutdown at
>> 120C, which is backwards. You should have:
>>
>> passive <= critical <= hardware
>Hmmm....
>but, the system will shutdown when temperature over critial value,
>there is no chance of triggering the TSHUT.
>
>If the temperature over a period of time High,as we know,
>the resulting TSHUT gave CRU module,let it hot-reset the entire chip,
>or via GPIO give PMIC cold-reset the entire chip.

Having tshut trigger is not the goal, tshut is the measure of last resort. If we can handle thermal conditions without triggering tshut, we achieved our goal.

Tshut triggering is " oh, crap, nothing we tried works" scenario.


Thanks.

-- 
Dmitry
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