linux-kernel - Re: [PATCH v8 04/16] clk: npcm8xx: add clock controller

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Date:   Mon, 8 Aug 2022 15:37:04 +0300
From:   Tomer Maimon <tmaimon77@...il.com>
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Avi Fishman <avifishman70@...il.com>,
        Benjamin Fair <benjaminfair@...gle.com>,
        Biju Das <biju.das.jz@...renesas.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Greg KH <gregkh@...uxfoundation.org>,
        Jonathan Neuschäfer <j.neuschaefer@....net>,
        Jiri Slaby <jirislaby@...nel.org>,
        Joel Stanley <joel@....id.au>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Lubomir Rintel <lkundrak@...sk>,
        Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        Michael Turquette <mturquette@...libre.com>,
        Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@...hiba.co.jp>,
        Olof Johansson <olof@...om.net>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Robert Hancock <robert.hancock@...ian.com>,
        Rob Herring <robh+dt@...nel.org>,
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        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Nancy Yuen <yuenn@...gle.com>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        SERIAL DRIVERS <linux-serial@...r.kernel.org>,
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        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v8 04/16] clk: npcm8xx: add clock controller

Hi Stephen,

Thanks for your reply.

On Thu, 4 Aug 2022 at 23:05, Stephen Boyd <sboyd@...nel.org> wrote:
>
> Quoting Tomer Maimon (2022-08-04 07:01:30)
> > On Sat, 30 Jul 2022 at 01:56, Stephen Boyd <sboyd@...nel.org> wrote:
> > >
> > > Because it is jumbled in some range?
> > Yes.
> > >
> > > >
> > > > I do see a way to combine the clock and the reset driver, the NPCM
> > > > reset driver is serving other NPCM BMC's.
> > > > Should we use regmap to handle the clock registers instead of ioremap?
> > >
> > > Sure? Using regmap or not looks like a parallel discussion. How does it
> > > help use platform APIs?
> > I mean to use regmap API instead of platform API for handing the clock
> > and reset registers.
> > the regmap API gives only one user access to R/W (lock).
> > I will be happy to get more suggestions, on how should we solve this situation.
> >
>
> Using platform APIs means using platform_*() functions, not of_*()
> functions, which are open-firmware/DT related. Regmap can be used to
> operate on registers mapped as __iomem, which is different from platform
> APIs.
I will use platform_get_resource() and devm_ioremap_resource()
functions in the next version.

>
> Is having a lock even necessary? Do the reset and clk controls live
You are right,  lock use is not necessary.
> within a shared register where we would need to prevent one driver from
> accessing that register at the same time as the other?
reset and clk drivers are living fine with shared registers, we don't
need to handle the register access between the clk and the reset
drivers.

Best regards,

Tomer