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

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Message-ID: <AM6PR04MB496607DD6E1B76E1B3A79C67806F0@AM6PR04MB4966.eurprd04.prod.outlook.com>
Date:   Tue, 30 Jun 2020 03:01:46 +0000
From:   Aisheng Dong <aisheng.dong@....com>
To:     Arnd Bergmann <arnd@...db.de>, Dong Aisheng <dongas86@...il.com>
CC:     Stephen Boyd <sboyd@...nel.org>, Abel Vesa <abel.vesa@....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" <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

> From: Arnd Bergmann <arnd@...db.de>
> Sent: Monday, June 29, 2020 4:20 PM
> 
> 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
> 

Yes, this seems better.
Anson, pls follow this way.

> > 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.
> 

Got it.

> 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?
> 

I guess we can find out them one by one for those 15 platforms when converting them
to modules as well. Currently we're converting ARM64 clock drivers first.

Regards
Aisheng

>        Arnd