linux-kernel - Re: [PATCH 0/3] Thermal reset support in PMC

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Date:	Wed, 13 Aug 2014 13:41:52 +0300
From:	Mikko Perttunen <mperttunen@...dia.com>
To:	Thierry Reding <thierry.reding@...il.com>
CC:	"swarren@...dotorg.org" <swarren@...dotorg.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH 0/3] Thermal reset support in PMC



On 13/08/14 13:36, Thierry Reding wrote:
> * PGP Signed by an unknown key
>
> On Wed, Aug 13, 2014 at 12:52:22PM +0300, Mikko Perttunen wrote:
>> On 13/08/14 11:57, Thierry Reding wrote:
>>>> Old Signed by an unknown key
>>>
>>> On Wed, Aug 13, 2014 at 11:42:53AM +0300, Mikko Perttunen wrote:
>>>>
>>>>
>>>> On 13/08/14 11:12, Mikko Perttunen wrote:
>>>>> On 13/08/14 11:07, Thierry Reding wrote:
>>>>>>> Old Signed by an unknown key
>>>>>>
>>>>>> On Tue, Aug 05, 2014 at 11:12:57AM +0300, Mikko Perttunen wrote:
>>>>>>> Hi,
>>>>>>>
>>>>>>> this series adds support for hardware-triggered thermal reset to the PMC
>>>>>>> driver. Namely, it adds device tree properties for specifying the I2C
>>>>>>> command to be sent when thermtrip is triggered. It is to be noted
>>>>>>> that thermtrip won't be ever triggered without a soctherm driver to
>>>>>>> calibrate the sensors, but I'll follow up with that patch.
>>>>>>>
>>>>>>> pmc.c required some juggling around to make the match data usable in
>>>>>>> probe, since I didn't want to put the code into the initcall either, since
>>>>>>> the soctherm driver won't be initialized by that point anyway.
>>>>>>>
>>>>>>> Series tested on Jetson-TK1. Should work on Tegra30 and Tegra114 too.
>>>>>>
>>>>>> Can you describe the procedure used to test this? We currently have a
>>>>>> bunch of features in Tegra that some people have tested at some point
>>>>>> during development but the test procedures never got documented. That
>>>>>> means whenever we want to test something we need to go and reinvent a
>>>>>> bunch of tests after the fact.
>>>>>>
>>>>>> So what I'd like to start doing is collect tests (preferably in some
>>>>>> scripted way) so that they can be kept in a repository that people can
>>>>>> easily clone and run on devices.
>>>>>>
>>>>>> Could you provide something like that for thermtrip?
>>>>>
>>>>> Sure. I'll see if I can make a just a test script or if a local patch is
>>>>> needed to test. Btw, I also have a pretty nice test script for EMC
>>>>> ready, and I agree that such a repository would be very nice.
>>>>
>>>> Here is a test program. It it works, the device with immediately shut down.
>>>>
>>>> https://gist.github.com/cyndis/66126c9c176b5f94a76f
>>>
>>> Is there a way to set the trip temperature without going through
>>> /dev/mem? I'd expect the device to have a sysfs interface of some
>>> sort.
>>
>> The thermtrip "device" isn't currently exposed in any way. If it were
>> exposed, I suppose it would be exposed as thermal zone devices, each with
>> one trip point. Even then, the thermal framework doesn't really support this
>> properly; none of the trip point types really apply to this kind of trip
>> point, and x86 systems don't expose their trips either.
>
> Okay. The reason why I asked is because I'm not sure yet that having C
> programs in the test suite would be good, so having something that's
> easily scriptable would be preferred.

I agree. Looks like Python's stdlib has mmap support, so maybe we could 
use that.

>
>> Anyway, since debugging is pretty much the only use case for modifying
>> the trip temperature, I thought adding the tz_devices would be a bit
>> overkill.
>
> An alternative could be a file in debugfs.

True, though there's the "don't expose dangerous stuff in debugfs" 
argument against that. I don't really have problem with it, though.
Although in this case I think the script approach would be good enough.

>
> Thierry
>
> * Unknown Key
> * 0x7F3EB3A1
>
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