linux-kernel - Re: [GIT PULL] Thermal management updates for v4.17-rc1

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Date:   Fri, 13 Apr 2018 11:19:40 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Cc:     Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        "Li, Philip" <philip.li@...el.com>
Subject: Re: [GIT PULL] Thermal management updates for v4.17-rc1

On 13/04/2018 11:08, Bartlomiej Zolnierkiewicz wrote:
> On Friday, April 13, 2018 11:00:43 AM Daniel Lezcano wrote:
>> On 13/04/2018 10:55, Bartlomiej Zolnierkiewicz wrote:
>>> On Friday, April 13, 2018 01:39:05 PM Zhang Rui wrote:
>>>> Hi, Eduardo,
>>>>
>>>> On 四, 2018-04-12 at 21:08 -0700, Eduardo Valentin wrote:
>>>>> Hello,
>>>>>
>>>>> On Thu, Apr 12, 2018 at 09:55:19AM -0700, Linus Torvalds wrote:
>>>>>>
>>>>>> On Wed, Apr 11, 2018 at 10:08 PM, Zhang Rui <rui.zhang@...el.com>
>>>>>> wrote:
>>>>>>>
>>>>>>>
>>>>>>> could you please illustrate me what the kconfig & warning is?
>>>>>> Just "make allmodconfig" and the warning is about a uninitialized
>>>>>> variable.
>>>>>>
>>>>>> Line 304 in drivers/thermal/samsung/exynos_tmu.c if my shell
>>>>>> history
>>>>>> is to be believed.
>>>>>>
>>>>>>                 Linus
>>>>> Yeah, this has also passed my local compilation error. Somehow my
>>>>> gcc4.9
>>>>> is not catching it. Using an older gcc (gcc4.6) does catch it.
>>>>>
>>>>> Anyways, given that the conversion functions are written to cover
>>>>> for unexpected cal_type, the right way of fixing this is to rewrite
>>>>> the conversion functions to allow for returning error codes and
>>>>> adjusting the callers as expected.
>>>>>
>>>>> Rui, bzolnier, please consider the following fix:
>>>>>
>>>> as it is late in this merge window, I'd prefer to
>>>> 1. drop all the thermal-soc material in the first pull request which I
>>>> will send out soon.
>>>> 2. you can prepare another pull request containing the thermal-soc
>>>> materials except the exynos fixes
>>>> 3. exynos fixes with the problem solved can be queued for -rc2 or
>>>> later.
>>>
>>> Could you please just merge the obvious fix from Arnd instead?
>>>
>>> [ it was posted two weeks ago and ACKed by me ]
>>>
>>> https://patchwork.kernel.org/patch/10313313/
>>
>> I'm not sure these are correct fixes.
>>
>> The change 480b5bfc16e1 tells:
>>
>> "There should be no functional changes caused by this patch."
>>
>> but the fix above returns 0 as a default value instead of '50' or '25'
>> for the 5440 and that impacts the threshold etc ...
>>
>> IMO, the correct fix would be to define a default value '50', override
>> it at init time to '25' if it is a 5440. And then the variable 'temp'
>> and 'temp_code' get this value in the default case.
> 
> It is okay to return 0 because this code-path (the default one) will be
> never hit by the driver (probe makes sure of it) - the default case is
> here is just to silence compilation errors..

The init function is making sure cal_type is one or another. Can you fix
it correctly by replacing the 'switch' by a 'if' instead of adding dead
branches to please gcc?

if (data->cal_type == TYPE_TWO_POINT_TRIMMING) {
	return ...;
}

return ...;

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