linux-kernel - Re: [PATCH v2 2/6] clocksource: msc313e: Add support for ssd20xd-based platforms

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Date:   Thu, 16 Dec 2021 19:18:28 +0100
From:   Romain Perier <romain.perier@...il.com>
To:     Daniel Palmer <daniel@...f.com>
Cc:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        DTML <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/6] clocksource: msc313e: Add support for
 ssd20xd-based platforms

Hi Daniel,

What do you think about the following description ?  :  "
    clocksource: msc313e: Add support for ssd20xd-based platforms

    On SSD20X family SoCs bootrom sets the divider for timer0 to run at
    12Mhz, while timer1 and timer2 are kept unchanged and defaut to ~432Mhz.
    There are no ways to reduce or divide these clocks in the clktree.
    However, These SoCs provide an internal "timer_divide" register that can
    act on this input clock. This commit adds support for this register,
    as timer1 and timer2 are used as clockevents these will run at 48Mhz.

    Signed-off-by: Romain Perier <romain.perier@...il.com>
"

Romain

Le mer. 15 déc. 2021 à 13:00, Daniel Palmer <daniel@...f.com> a écrit :
>
> Hi Romain,
>
> On Mon, 13 Dec 2021 at 03:19, Romain Perier <romain.perier@...il.com> wrote:
> >
> > SSD20X family SoCs have an oscillator running at ~432Mhz for timer1 and
> > timer2, while timer0 is running at 12Mhz.
>
> I don't think this is technically true. I think the boot rom sets the
> divider for timer0 so that it runs at ~12MHz.
> I think the current change to only configure timer1 and timer2 is ok
> but maybe the commit message should say that timer0 is configured to
> be backwards compatible at boot.
>
> Cheers,
>
> Daniel