linux-kernel - Re: [RFC 3/3] ARM: dts: Don't overheat the Odroid XU3-Lite on high load

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Message-id: <56C659DE.8010402@samsung.com>
Date:	Fri, 19 Feb 2016 08:55:10 +0900
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Marek Szyprowski <m.szyprowski@...sung.com>,
	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	Anand Moon <linux.amoon@...il.com>, Kukjin Kim <kgene@...nel.org>,
	Lukasz Majewski <l.majewski@...sung.com>,
	linux-arm-kernel@...ts.infradead.org,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Zhang Rui <rui.zhang@...el.com>,
	Eduardo Valentin <edubezval@...il.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Javier Martinez Canillas <javier@....samsung.com>
Subject: Re: [RFC 3/3] ARM: dts: Don't overheat the Odroid XU3-Lite on high load

On 18.02.2016 18:59, Marek Szyprowski wrote:
> Hello,
> 
> On 2016-02-18 05:42, Krzysztof Kozlowski wrote:
>> On 18.02.2016 11:36, Viresh Kumar wrote:
>>>> BTW, I found the issue. The order of trip points in DT:
>>>> thermal_zone0/trip_point_0_hyst:5000
>>>> thermal_zone0/trip_point_0_temp:50000
>>>> thermal_zone0/trip_point_0_type:active
>>>> thermal_zone0/trip_point_1_hyst:5000
>>>> thermal_zone0/trip_point_1_temp:60000
>>>> thermal_zone0/trip_point_1_type:active
>>>> thermal_zone0/trip_point_2_hyst:5000
>>>> thermal_zone0/trip_point_2_temp:70000
>>>> thermal_zone0/trip_point_2_type:active
>>>> thermal_zone0/trip_point_3_hyst:0
>>>> thermal_zone0/trip_point_3_temp:120000    <---- this should be last
>>>> one!
>>>> thermal_zone0/trip_point_3_type:critical
>>>> thermal_zone0/trip_point_4_hyst:5000
>>>> thermal_zone0/trip_point_4_temp:90000
>>>> thermal_zone0/trip_point_4_type:passive
>>>> thermal_zone0/trip_point_5_hyst:5000
>>>> thermal_zone0/trip_point_5_temp:110000
>>>> thermal_zone0/trip_point_5_type:passive
>>>>
>>>> After fixing the order in DT, the cpu cooler starts working.
>>> Ahh, nice.
>> Damn, not entirely. I almost fried my Odroid (it survived 130 degrees of
>> C)... The TMU supports only 4 trip points, so when I added two new trip
>> points and reordered them... the last two (including critical) was not
>> receiving interrupts.
>>
>> Polling mode is needed. I'll sent some patches soon...
> 
> Instead of polling the driver should simply use some dynamic window for
> the nearest temperature ranges and reconfigure it when interrupt of occurs.


Thanks for feedback, Marek!

First of all the polling happens only when initial trip point for
passive cooling is reached (70 degrees C). This fortunately reduces the
polling overhead.

Yours idea seems interesting... but driver does not support it now, does
it? I can put this on TODO list, maybe someone will extend the exynos
thermal driver.

Best regards,
Krzysztof