linux-kernel - Re: [RFC PATCH 2/3] clk: bd718x7: Enable the possibility to mark the clock as critical

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Date:   Mon, 6 Jun 2022 08:08:45 +0200
From:   Michael Nazzareno Trimarchi <michael@...rulasolutions.com>
To:     Matti Vaittinen <mazziesaccount@...il.com>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        "open list:COMMON CLK FRAMEWORK" <linux-clk@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        Dario Binacchi <dario.binacchi@...rulasolutions.com>,
        linux-amarula@...rulasolutions.com, Marek Vasut <marex@...x.de>
Subject: Re: [RFC PATCH 2/3] clk: bd718x7: Enable the possibility to mark the
 clock as critical

Hi

On Mon, Jun 6, 2022 at 7:26 AM Matti Vaittinen <mazziesaccount@...il.com> wrote:
>
> Hi Michael,
>
> On 6/5/22 19:57, Michael Trimarchi wrote:
> > If the clock is used to generate the osc_32k, we need to mark
> > as critical. clock-critical has no binding description at the moment
> > but it's defined in linux kernel
> >
> > bd71847: pmic@4b {
> > ...
> >       rohm,reset-snvs-powered;
> >
> >       #clock-cells = <0>;
> >       clock-critical = <1>;
> >       clocks = <&osc_32k 0>;
> >       clock-output-names = "clk-32k-out";
> > ...
> > }
> >
> > Signed-off-by: Michael Trimarchi <michael@...rulasolutions.com>
> > ---
> >   drivers/clk/clk-bd718x7.c | 4 ++++
>
> //snip
>
> > @@ -100,6 +101,9 @@ static int bd71837_clk_probe(struct platform_device *pdev)
> >
> >       parent_clk = of_clk_get_parent_name(parent->of_node, 0);
> >
> > +     of_clk_detect_critical(dev->of_node, 0, &flags);
>
> Purely judging the kerneldoc for of_clk_detect_critical - you may have
> hard time getting this accepted.
>

This is the reason for RFC. I have already seen the usage of this in

ainline/master:drivers/clk/st/clk-flexgen.c:
of_clk_detect_critical(np, i, &flex_flags);
mainline/master:drivers/clk/st/clkgen-fsyn.c:
of_clk_detect_critical(np, fschan, &flags);
mainline/master:drivers/clk/st/clkgen-pll.c:
of_clk_detect_critical(np, 0, &pll_flags);
mainline/master:drivers/clk/st/clkgen-pll.c:
of_clk_detect_critical(np, odf, &odf_flags);

> I think you're working on a very valid problem though. Maybe you could
> see if you could align your effort with Marek?
>
> https://lore.kernel.org/all/20220517235919.200375-1-marex@denx.de/T/#m52d6d0831bf43d5f293e35cb27f3021f278d0564
>

I have seen the Marek patcheset now. I don't know if they works anyway
for a clock that is a part of MFD controller

Michael

> Best Regards
>         -- Matti
>
> --
> Matti Vaittinen
> Linux kernel developer at ROHM Semiconductors
> Oulu Finland
>
> ~~ When things go utterly wrong vim users can always type :help! ~~
>
> Discuss - Estimate - Plan - Report and finally accomplish this:
> void do_work(int time) __attribute__ ((const));



-- 
Michael Nazzareno Trimarchi
Co-Founder & Chief Executive Officer
M. +39 347 913 2170
michael@...rulasolutions.com
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