linux-kernel - Re: [PATCH] arm64: dts: rockchip: rk3399: Add xin32k clk

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Date:   Mon, 19 Nov 2018 18:05:52 -0800
From:   "dbasehore ." <dbasehore@...omium.org>
To:     Heiko Stübner <heiko@...ech.de>
Cc:     Doug Anderson <dianders@...omium.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-rockchip@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        谢修鑫 <tony.xie@...k-chips.com>,
        Chris Zhong <zyw@...k-chips.com>, ayaka@...lik.info,
        "nickey.yang" <nickey.yang@...k-chips.com>,
        Shunqian Zheng <zhengsq@...k-chips.com>,
        klaus.goger@...obroma-systems.com,
        Brian Norris <briannorris@...omium.org>,
        enric.balletbo@...labora.com, Mark Rutland <mark.rutland@....com>,
        robh+dt@...nel.org
Subject: Re: [PATCH] arm64: dts: rockchip: rk3399: Add xin32k clk

On Mon, Nov 19, 2018 at 1:41 AM Heiko Stübner <heiko@...ech.de> wrote:
>
> Am Freitag, 16. November 2018, 19:23:59 CET schrieb Doug Anderson:
> > Hi,
> >
> > On Fri, Nov 16, 2018 at 9:39 AM dbasehore . <dbasehore@...omium.org> wrote:
> > > On Fri, Nov 16, 2018 at 8:01 AM Doug Anderson <dianders@...omium.org>
> wrote:
> > > > Hi,
> > > >
> > > > On Thu, Nov 15, 2018 at 9:17 PM Derek Basehore <dbasehore@...omium.org>
> wrote:
> > > > > This adds the xin32k clock to the RK3399 CPU. Even though it's not
> > > > > directly used, muxes will end up traversing the entire clk tree on
> > > > > calls to determine_rate if it doesn't exist.
> > > > >
> > > > > Signed-off-by: Derek Basehore <dbasehore@...omium.org>
> > > > > ---
> > > > >
> > > > >  arch/arm64/boot/dts/rockchip/rk3399.dtsi | 7 +++++++
> > > > >  1 file changed, 7 insertions(+)
> > > >
> > > > nit: I would have expected ${SUBJECT} to have v2 in it somewhere.
> > > >
> > > > > diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> > > > > b/arch/arm64/boot/dts/rockchip/rk3399.dtsi index
> > > > > 99e7f65c1779..3d09472978f8 100644
> > > > > --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> > > > > +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> > > >
> > > > Aww crud.  I was at the airport yesterday and so I didn't notice that
> > > > you were touching rk3399, not rk3399-gru.  This belongs in the gru
> > > > device tree file, not in the top level rk3399.  As you have written
> > >
> > > > this it will break rk3399 boards that have an rk808 on them, AKA:
> > > Should this be moved to the rk3399.dtsi file? The RK3399 assumes that
> > > this clk exists (same as the 24MHz clk which is in rk3399.dtsi). While
> > > it can function without it defined, it really shouldn't. We can just
> > > assign the existing labels in the dts files you pointed out.
> >
> > No, it should be in the board files.  Each board may produce the 32k
> > clock through a different component.  On gru-based devices we produce
> > the 32k clock through a silego part.
>
> That would also be a great part of the commit message, like
> "...on Gru boards the 32kHz clock gets produced by a Silego oscillator"
> or so when you move it over to rk3399-gru.dtsi .
>
>
> > Technically you could say that we don't _truly_ need to model this
> > clock and we could have just inserted a dummy/fixed 32k clock in the
> > clk-rk3399.c file.  ...but we did model it so that means we should
> > probably model it semi-properly.
> >
> > If a given board forgets to provide a 32k clock then that's a bug for
> > them like it was for us.
>
> Yep and as I said in my other mail, on these pmic generated clocks
> the clock generation often even is configurable (rate, on/off), so it
> should really be a real clock not some hack ;-) .
>

Ok, I'll make that change in about a week after I get back from
vacation in about a week.

>
> Heiko
>
>