linux-kernel - Re: [PATCH 01/18] arm64: dts: renesas: beacon kit: Configure programmable clocks

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Date:   Thu, 17 Dec 2020 09:16:44 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Adam Ford <aford173@...il.com>
Cc:     Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Adam Ford-BE <aford@...conembedded.com>,
        Magnus Damm <magnus.damm@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Luca Ceresoli <luca@...aceresoli.net>
Subject: Re: [PATCH 01/18] arm64: dts: renesas: beacon kit: Configure
 programmable clocks

Hi Adam,

On Wed, Dec 16, 2020 at 6:03 PM Adam Ford <aford173@...il.com> wrote:
> On Wed, Dec 16, 2020 at 8:55 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> > On Sun, Dec 13, 2020 at 7:38 PM Adam Ford <aford173@...il.com> wrote:
> > > When the board was added, clock drivers were being updated done at
> > > the same time to allow the versaclock driver to properly configure
> > > the modes.  Unforutnately, the updates were not applied to the board

> > > --- a/arch/arm64/boot/dts/renesas/beacon-renesom-baseboard.dtsi
> > > +++ b/arch/arm64/boot/dts/renesas/beacon-renesom-baseboard.dtsi
> > > @@ -5,6 +5,7 @@
> > >
> > >  #include <dt-bindings/gpio/gpio.h>
> > >  #include <dt-bindings/input/input.h>
> > > +#include <dt-bindings/clk/versaclock.h>
> > >
> > >  / {
> > >         backlight_lvds: backlight-lvds {
> > > @@ -294,12 +295,12 @@ &du_out_rgb {
> > >  &ehci0 {
> > >         dr_mode = "otg";
> > >         status = "okay";
> > > -       clocks = <&cpg CPG_MOD 703>, <&cpg CPG_MOD 704>;
> > > +       clocks = <&cpg CPG_MOD 703>, <&cpg CPG_MOD 704>, <&versaclock5 3>;
> >
> > Why this change? You said before you don't need this
> > https://lore.kernel.org/linux-renesas-soc/CAHCN7xJWbP16SA-Ok-5syNnqOZAt8OFJo2_rtg5VrNVsN2-eiQ@mail.gmail.com/
> >
>
> I had talked with the hardware guys about buy pre-programmed
> versaclock chips which would have been pre-configured and pre-enabled.
> I thought it was going to happen, but it didn't, so we need the
> versaclock driver to enable the reference clock for the USB
> controllers, ethernet controller and audio clocks.  Previously we were
> manually configuring it or it was coincidentally working. Ideally,
> we'd have the clock system intentionally enable/disable the clocks
> when drivers are loaded/unloaded for for power management reasons.

Can you tell me how exactly the Versaclock outputs are wired?
E.g. for USB, the bindings don't say anything about a third clock input,
so I'd like to know where that clock is fed into USB.

> Thank you for the review.  Is that the only patch in the series with
> concerns?  I probably won't get to V2 until this weekend.

Sorry, I still have to review the other patches in your series.
Anyway, we have time until the end of January to queue DT patches for
v5.12...

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds