linux-kernel - Re: [PATCH V2 3/9] clk: imx: Support building SCU clock driver as module

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Message-ID: <CAK8P3a2-1nFvw2rR1wws04fCmj6AyvcJ4RFwcJQ+xRPwDjUCaA@mail.gmail.com>
Date:   Mon, 29 Jun 2020 10:19:44 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Dong Aisheng <dongas86@...il.com>
Cc:     Stephen Boyd <sboyd@...nel.org>, Abel Vesa <abel.vesa@....com>,
        Aisheng Dong <aisheng.dong@....com>,
        Andy Duan <fugang.duan@....com>,
        Anson Huang <anson.huang@....com>,
        Daniel Baluta <daniel.baluta@....com>,
        Leonard Crestez <leonard.crestez@....com>,
        Peng Fan <peng.fan@....com>,
        Stefan Agner <stefan.agner@...adex.com>,
        Allison Randal <allison@...utok.net>,
        Fabio Estevam <festevam@...il.com>,
        gregkh <gregkh@...uxfoundation.org>,
        Enrico Weigelt <info@...ux.net>,
        Sascha Hauer <kernel@...gutronix.de>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        Russell King <linux@...linux.org.uk>,
        Michael Turquette <mturquette@...libre.com>,
        oleksandr.suvorov@...adex.com,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Shawn Guo <shawnguo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        YueHaibing <yuehaibing@...wei.com>,
        dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH V2 3/9] clk: imx: Support building SCU clock driver as module

On Mon, Jun 29, 2020 at 9:18 AM Dong Aisheng <dongas86@...il.com> wrote:
> On Thu, Jun 25, 2020 at 6:43 AM Stephen Boyd <sboyd@...nel.org> wrote:
> > Quoting Aisheng Dong (2020-06-23 19:59:09)
> > Why aren't there options to enable clk-imx6q and clk-imx6sl in the
> > clk/imx/Kconfig file? Those can be bool or tristate depending on if the
> > SoC drivers use CLK_OF_DECLARE or not and depend on the mxc-clk library
> > and SoC config we have in the makefile today.
>
> Yes, we can do that in clk/imx/Kconfig as follows theoretically.
> config CLK_IMX6Q
>         bool
>         def_bool ARCH_MXC && ARM
>         select MXC_CLK
>
> But we have totally 15 platforms that need to change.

I would make that

config CLK_IMX6Q
         bool "Clock driver for NXP i.MX6Q"
         depends on SOC_IMX6Q || COMPILE_TEST
         default SOC_IMX6Q
         select MXC_CLK

> e.g.
> drivers/clk/imx/Makefile
> obj-$(CONFIG_SOC_IMX1)   += clk-imx1.o
> obj-$(CONFIG_SOC_IMX21)  += clk-imx21.o
> obj-$(CONFIG_SOC_IMX25)  += clk-imx25.o
> obj-$(CONFIG_SOC_IMX27)  += clk-imx27.o
> obj-$(CONFIG_SOC_IMX31)  += clk-imx31.o
> obj-$(CONFIG_SOC_IMX35)  += clk-imx35.o
> obj-$(CONFIG_SOC_IMX5)   += clk-imx5.o
> obj-$(CONFIG_SOC_IMX6Q)  += clk-imx6q.o
> obj-$(CONFIG_SOC_IMX6SL) += clk-imx6sl.o
> obj-$(CONFIG_SOC_IMX6SLL) += clk-imx6sll.o
> obj-$(CONFIG_SOC_IMX6SX) += clk-imx6sx.o
> obj-$(CONFIG_SOC_IMX6UL) += clk-imx6ul.o
> obj-$(CONFIG_SOC_IMX7D)  += clk-imx7d.o
> obj-$(CONFIG_SOC_IMX7ULP) += clk-imx7ulp.o
> obj-$(CONFIG_SOC_VF610)  += clk-vf610.o
>
> Not sure if it's really worth to do that.
> The easiest way to address this issue is just select it in
> arch/arm/mach-imx/Kconfig,

Changing them can be a one or two patches, that's totally
worth it IMHO.

I really don't like the 'select' in arch/arm/mach-imx/Kconfig: if
you've done the work to make the imx8 clk driver modular,
I would expect to see the same at least tried for the other
ones.

For the clk drivers that cannot yet be 'tristate' because of the
CLK_OF_DECLARE(), can you include a list of drivers
that depend on the clocks being available during early
boot?

       Arnd