Re: [PATCH] thermal: of: Allow selection of thermal governor in DT

From: Daniel Lezcano <daniel.lezcano@linaro.org>
To: Amit Kucheria <amit.kucheria@linaro.org>
Cc: DTML <devicetree@vger.kernel.org>,
	Ram Chandrasekar <rkumbako@codeaurora.org>,
	Lina Iyer <ilina@codeaurora.org>, Zhang Rui <rui.zhang@intel.com>,
	Eduardo Valentin <edubezval@gmail.com>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Linux PM list <linux-pm@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] thermal: of: Allow selection of thermal governor in DT
Date: Tue, 6 Mar 2018 16:43:04 +0100	[thread overview]
Message-ID: <4e3cc8a6-4b4b-4b09-5c04-b7b331158339@linaro.org> (raw)
In-Reply-To: <CAP245DWvBjcS73YhPxwh2OKW_PYvBLTe-ay6XD8VrSWpukQ3CQ@mail.gmail.com>

On 06/03/2018 06:48, Amit Kucheria wrote:
> On Tue, Mar 6, 2018 at 2:41 AM, Daniel Lezcano
> <daniel.lezcano@linaro.org> wrote:
>> On 05/03/2018 19:36, Amit Kucheria wrote:
>>> From: Ram Chandrasekar <rkumbako@codeaurora.org>
>>>
>>> There is currently no way for the governor to be selected for each thermal
>>> zone in devicetree. This results in the default governor being used for all
>>> thermal zones even though no such restriction exists in the core code.
>>>
>>> Add support for specifying the thermal governor to be used for a thermal
>>> zone in the devicetree. The devicetree config should specify the governor
>>> name as a string that matches any available governors. If not specified, we
>>> maintain the current behaviour of using the default governor.
>>>
>>> Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>
>>> Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>
>>
>> Why not create a kernel parameter (eg. thermal.governor=) ? So everyone
>> can gain benefit of this feature. And in order to specify that from the
>> DT, add the 'chosen' node and bootargs with the desired kernel parameter?
>>
> 
> This is supposed to be a per-thermal zone property. So specifying it
> on the command-line, while possible, might be a little cumbersome. I'm
> not even sure if kernel parameters can have a variable number of
> arguments. IOW, thermal.tz0.governor=userspace,
> thermal.tz1.governor=step_wise, thermal.tz2.governor=userspace, .....
> 
> I'm already seeing SoCs defining 8 or more thermal zones.

Ah yes indeed.

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