linux-kernel - RE: [PATCH 2/7] clk: renesas: r8a77965: Add DAB clock

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Message-ID: <OSAPR01MB2737B48A9C32BE7162BB701AC29A9@OSAPR01MB2737.jpnprd01.prod.outlook.com>
Date:   Mon, 1 Mar 2021 15:01:14 +0000
From:   Fabrizio Castro <fabrizio.castro.jz@...esas.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
CC:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Rob Herring <robh+dt@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux API <linux-api@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Chris Paterson <Chris.Paterson2@...esas.com>,
        Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>,
        Phil Edworthy <phil.edworthy@...esas.com>,
        "REE dirk.behme@...bosch.com" <dirk.behme@...bosch.com>,
        Peter Erben <Peter.Erben@...bosch.com>
Subject: RE: [PATCH 2/7] clk: renesas: r8a77965: Add DAB clock

Hi Laurent,

Thanks for your feedback!

> From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> Sent: 26 February 2021 12:49
> Subject: Re: [PATCH 2/7] clk: renesas: r8a77965: Add DAB clock
> 
> Hi Fabrizio,
> 
> Thank you for the patch.
> 
> On Fri, Feb 26, 2021 at 09:45:20AM +0100, Geert Uytterhoeven wrote:
> > On Thu, Feb 25, 2021 at 11:53 PM Fabrizio Castro wrote:
> > > This patch adds the DAB clock to the R8A77965 SoC.
> > >
> > > Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
> >
> > Thanks for your patch!
> >
> > > --- a/drivers/clk/renesas/r8a77965-cpg-mssr.c
> > > +++ b/drivers/clk/renesas/r8a77965-cpg-mssr.c
> > > @@ -250,6 +250,7 @@ static const struct mssr_mod_clk
> r8a77965_mod_clks[] __initconst = {
> > >         DEF_MOD("ssi2",                 1013,   MOD_CLK_ID(1005)),
> > >         DEF_MOD("ssi1",                 1014,   MOD_CLK_ID(1005)),
> > >         DEF_MOD("ssi0",                 1015,   MOD_CLK_ID(1005)),
> > > +       DEF_MOD("dab",                  1016,   R8A77965_CLK_S0D6),
> >
> > Unfortunately this bit is not documented in the R-Car Gen3 Hardware
> > User's Manual, so I have to trust you on this.
> >
> > While it's not unusual that the same module on R-Car E3 and M3-N
> > has different parent clocks, it does strike me as odd that S0D6 on M3-N
> > runs at 133 MHz, while S3D1 on E3 runs at 266 MHz.
> > Probably it doesn't matter that much, as your driver doesn't care
> > about the actual clock rate.
> 
> I have the exact same concerns, here and for 1/7.

I hear you, but you know how these sort of things go, a bit was left
behind, now they are aware of this bit missing from the documentation
and at some point they will release a document addressing this particular
point. Meanwhile, we have received written confirmation for this, so
it should be okay.

Thanks,
Fab

> 
> > >         DEF_MOD("scu-all",              1017,   R8A77965_CLK_S3D4),
> > >         DEF_MOD("scu-dvc1",             1018,   MOD_CLK_ID(1017)),
> > >         DEF_MOD("scu-dvc0",             1019,   MOD_CLK_ID(1017)),
> 
> --
> Regards,
> 
> Laurent Pinchart