linux-kernel - Re: [PATCH 4/5] clk: meson: meson8b: don't register the XTAL clock when provided via OF

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Date:   Mon, 23 Sep 2019 22:57:19 +0200
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     Jerome Brunet <jbrunet@...libre.com>
Cc:     Neil Armstrong <narmstrong@...libre.com>, robh+dt@...nel.org,
        mark.rutland@....com, linux-amlogic@...ts.infradead.org,
        devicetree@...r.kernel.org, khilman@...libre.com,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH 4/5] clk: meson: meson8b: don't register the XTAL clock
 when provided via OF

On Mon, Sep 23, 2019 at 11:31 AM Jerome Brunet <jbrunet@...libre.com> wrote:
>
> On Sat 21 Sep 2019 at 17:12, Martin Blumenstingl <martin.blumenstingl@...glemail.com> wrote:
>
> > The XTAL clock is an actual crystal on the PCB. Thus the meson8b clock
> > driver should not register the XTAL clock - instead it should be
> > provided via .dts and then passed to the clock controller.
> >
> > Skip the registration of the XTAL clock if a parent clock is provided
> > via OF. Fall back to registering the XTAL clock if this is not the case
> > to keep support for old .dtbs.
> >
> > Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
> > ---
> >  drivers/clk/meson/meson8b.c | 12 +++++++++---
> >  1 file changed, 9 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/clk/meson/meson8b.c b/drivers/clk/meson/meson8b.c
> > index b785b67baf2b..15ec14fde2a0 100644
> > --- a/drivers/clk/meson/meson8b.c
> > +++ b/drivers/clk/meson/meson8b.c
> > @@ -3682,10 +3682,16 @@ static void __init meson8b_clkc_init_common(struct device_node *np,
> >               meson8b_clk_regmaps[i]->map = map;
> >
> >       /*
> > -      * register all clks
> > -      * CLKID_UNUSED = 0, so skip it and start with CLKID_XTAL = 1
> > +      * always skip CLKID_UNUSED and also skip XTAL if the .dtb provides the
> > +      * XTAL clock as input.
> >        */
> > -     for (i = CLKID_XTAL; i < CLK_NR_CLKS; i++) {
> > +     if (of_clk_get_parent_count(np))
>
> If we are going for this, I'd prefer if could explicity check for the
> clock named "xtal" instead of just checking if DT has clocks.
OK, I'll wait a few days and then fix this in v2


Martin