linux-kernel - Re: [PATCH 2/6] thermal: of: Export non-devres helper to register/unregister thermal zone

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Message-ID: <b496d933-3c57-4b02-ab65-0582a30939af@linaro.org>
Date: Thu, 30 Jan 2025 18:24:41 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Claudiu Beznea <claudiu.beznea@...on.dev>
Cc: rafael@...nel.org, rui.zhang@...el.com, lukasz.luba@....com,
 robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
 geert+renesas@...der.be, magnus.damm@...il.com, mturquette@...libre.com,
 sboyd@...nel.org, p.zabel@...gutronix.de, ulf.hansson@...aro.org,
 linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org,
 Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH 2/6] thermal: of: Export non-devres helper to
 register/unregister thermal zone

On 30/01/2025 11:30, Claudiu Beznea wrote:
> 
> 
> On 30.01.2025 12:07, Daniel Lezcano wrote:
>> On Thu, Jan 30, 2025 at 11:08:03AM +0200, Claudiu Beznea wrote:
>>> Hi, Daniel,

[ ... ]

>>>> Would the IP need some cycles to capture the temperature accurately after the
>>>> clock is enabled ?
>>>
>>> There is nothing about this mentioned about this in the HW manual of the
>>> RZ/G3S SoC. The only points mentioned are as described in the driver code:
>>> - wait at least 3us after each IIO channel read
>>> - wait at least 30us after enabling the sensor
>>> - wait at least 50us after setting OE bit in TSU_SM
>>>
>>> For this I chose to have it implemented as proposed.
>>
>> IMO, disabling/enabling the clock between two reads through the pm runtime may
>> not be a good thing, especially if the system enters a thermal situation where
>> it has to mitigate.
>>
>> Without any testing capturing the temperatures and compare between the always-on
>> and on/off, it is hard to say if it is true or not. Up to you to test that or
>> not. If you think it is fine, then let's go with it.
> 
> I tested it with and w/o the runtime PM and on/off support (so, everything
> ON from the probe) and the reported temperature values were similar.


Did you remove the roundup to 0.5°C ?


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