Re: [PATCH 04/11] thermal: exynos: remove fine-grained clk management

[Krzysztof Kozlowski]

On 01/09/2023 10:40, Marek Szyprowski wrote:
> On 29.08.2023 11:56, Krzysztof Kozlowski wrote:
>> On 29/08/2023 11:18, Mateusz Majewski wrote:
>>> This clock only controls the register operations. The gain in power
>>> efficiency is therefore quite dubious, while there is price of added
>>> complexity that is important to get right (as a register operation might
>>> outright hang the CPU if the clock is not enabled).
>> So once it is done right, this stops being argument. The benefit is to
>> keep this clock disabled most of the time, which now we lost.
>>
>> I don't find this patch correct approach.
> 
> I've suggested this change while playing with this driver.
> 
> For me turning AHB clock on/off during normal driver operation seems to 
> be over-engineering and really gives no real power saving benefits, 
> especially if thermal driver is the only one that does such fine-grained 
> clock management (none of the Exynos supported in mainline does that). 
> Removing it simplifies code and makes it easier to understand or read, 
> as the current code already was somehow problematic to understand and 
> unintuitive:
> 
> https://lore.kernel.org/all/c3258cb2-9a56-d048-5738-1132331a157d@xxxxxxxxxx/
> 
> Taking into account that the driver is not really maintained, making it 
> simpler without noticeable feature loss counts as a benefit for me.

Hm, ok, let it be, although I bet once someone will come and start
adding runtime PM for clock handling...

Best regards,
Krzysztof