linux-kernel - Re: [PATCH] clk: renesas: r9a07g044: Add WDT2 clocks to critical list

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Date:   Mon, 19 Sep 2022 15:16:00 +0100
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:     Biju Das <biju.das.jz@...renesas.com>
Cc:     Geert Uytterhoeven <geert+renesas@...der.be>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH] clk: renesas: r9a07g044: Add WDT2 clocks to critical list

Hi Biju,

On Mon, Sep 19, 2022 at 2:52 PM Biju Das <biju.das.jz@...renesas.com> wrote:
>
> Hi Prabhakar,
>
> > Subject: Re: [PATCH] clk: renesas: r9a07g044: Add WDT2 clocks to
> > critical list
> >
> > Hi Biju,
> >
> > On Mon, Sep 19, 2022 at 2:35 PM Biju Das <biju.das.jz@...renesas.com>
> > wrote:
> > >
> > > Hi Prabhakar,
> > >
> > > > Subject: [PATCH] clk: renesas: r9a07g044: Add WDT2 clocks to
> > > > critical list
> > > >
> > > > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > > >
> > > > Add the WDT2 clocks to r9a07g044_crit_mod_clks[] list as WDT CH2
> > is
> > > > specifically to check the operation of Cortex-M33 CPU on the
> > > > RZ/{G2L, G2LC, V2L} SoCs and we dont want to turn off the clocks
> > of
> > > > WDT2 if it isn't enabled by Cortex-A55.
> > > >
> > > > This patch is in preparation to disable WDT CH2 from the RZ/G2L
> > > > (alike
> > > > SoCs) DTS/I by default.
> > > >
> > > > Reported-by: Biju Das <biju.das.jz@...renesas.com>
> > > > Signed-off-by: Lad Prabhakar
> > > > <prabhakar.mahadev-lad.rj@...renesas.com>
> > > > ---
> > > >  drivers/clk/renesas/r9a07g044-cpg.c | 2 ++
> > > >  1 file changed, 2 insertions(+)
> > > >
> > > > diff --git a/drivers/clk/renesas/r9a07g044-cpg.c
> > > > b/drivers/clk/renesas/r9a07g044-cpg.c
> > > > index 02a4fc41bb6e..cf9b1bd73792 100644
> > > > --- a/drivers/clk/renesas/r9a07g044-cpg.c
> > > > +++ b/drivers/clk/renesas/r9a07g044-cpg.c
> > > > @@ -412,6 +412,8 @@ static const unsigned int
> > > > r9a07g044_crit_mod_clks[] __initconst = {
> > > >       MOD_CLK_BASE + R9A07G044_GIC600_GICCLK,
> > > >       MOD_CLK_BASE + R9A07G044_IA55_CLK,
> > > >       MOD_CLK_BASE + R9A07G044_DMAC_ACLK,
> > > > +     MOD_CLK_BASE + R9A07G044_WDT2_PCLK,
> > > > +     MOD_CLK_BASE + R9A07G044_WDT2_CLK,
> > >
> > > Do we need to turn on this clock unnecessarily?
> > >
> > No, this is in preparation to disable WDT2 by default from RZ/G2L{C}
> > DTS/I.
>
> But that will make WDT2 device is not enabled, but unnecessarily the clk is on.
>
Agreed the clocks will be ON, but didnt we agree earlier for r9a07g043-cpg.c?

> Not sure, If we have any use case for wdt2 controlling from CA-55??
> If there is no use case, why can't we remove it from SoC dtsi and clock tables,
> that why we don't unnecessarily use this clock anymore??
>
I dont have a clear use case of using WDT ch2 when trying to use it
from CA-55 either.

Cheers,
Prabhakar