linux-kernel - Re: [PATCH 0/2] clk: renesas: rzg2l: Disable unused clocks after resume

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Message-ID: <0d71269f-1c78-4732-8235-5640bf340d00@tuxon.dev>
Date: Tue, 26 Aug 2025 14:01:56 +0300
From: claudiu beznea <claudiu.beznea@...on.dev>
To: Brian Masney <bmasney@...hat.com>
Cc: mturquette@...libre.com, sboyd@...nel.org, geert+renesas@...der.be,
 linux@...linux.org.uk, linux-renesas-soc@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org,
 linux-kernel@...r.kernel.org,
 Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH 0/2] clk: renesas: rzg2l: Disable unused clocks after
 resume

Hi, Brian,

On 8/25/25 20:05, Brian Masney wrote:
> Hi Claudiu,
> 
> On Thu, Aug 21, 2025 at 11:03:30AM +0300, Claudiu wrote:
>> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>>
>> Hi,
>>
>> This series disables clocks that remain unused after resume.
>> This is necessary when the resume process is done with the help of the
>> bootloader, as the bootloader enables various clocks when returning from
>> resume.
>>
>> On the RZ/G3S SoC (where this series was tested), the bootloader enables
>> the SDHI clocks (for all SDHI modules, of which 2 are used by Linux and
>> 1 is unused) and the clocks for a serial IP (unused by Linux).
>>
>> Testing was done on the RZ/G3S SMARC Carrier II board.
> 
> Do you think that other boards would also benefit from this change? If
> so, what do you think about putting the call to register_pm_notifier()
> inside an __init block in clk.c so that this same change doesn't have to
> be implemented across various clk drivers?

Yes, that was my other approach I was thinking about. I wanted to see how other 
people consider this version.

> 
> Alternatively, if this is board specific, could this be fixed in the
> boot loader so that the clock that's not used by Linus is properly shut
> down on resume?

As a result of your request I did some more investigations on my side, I can say 
that, yes, in theory that could be also handled by bootloader.

I can drop this and try to do it in bootloader, if any. Please let me know if 
you still consider this (or the variant that implements it in a generic way) 
necessary.

Thank you for your review,
Claudiu

> 
> I'm not the subsystem maintainer, so I'm not asking you to make any of
> these changes.
> 
> Brian
>