linux-kernel - RE: [PATCH V5 1/9] pinctrl: imx: Support building SCU pinctrl driver as module

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Date:   Wed, 17 Jun 2020 10:29:46 +0000
From:   Aisheng Dong <aisheng.dong@....com>
To:     Anson Huang <anson.huang@....com>,
        "festevam@...il.com" <festevam@...il.com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "stefan@...er.ch" <stefan@...er.ch>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "linus.walleij@...aro.org" <linus.walleij@...aro.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
CC:     dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH V5 1/9] pinctrl: imx: Support building SCU pinctrl driver
 as module

[...]

> > > > > - * @dev: a pointer back to containing device
> > > > > - * @base: the offset to the controller in virtual memory
> > > > > - */
> > > > > -struct imx_pinctrl {
> > > > > -	struct device *dev;
> > > > > -	struct pinctrl_dev *pctl;
> > > > > -	void __iomem *base;
> > > > > -	void __iomem *input_sel_base;
> > > > > -	const struct imx_pinctrl_soc_info *info;
> > > > > -	struct imx_pin_reg *pin_regs;
> > > > > -	unsigned int group_index;
> > > > > -	struct mutex mutex;
> > > > > +	int (*imx_pinconf_get)(struct pinctrl_dev *pctldev, unsigned
> > > > > +int
> > pin_id,
> > > > > +			       unsigned long *config);
> > > > > +	int (*imx_pinconf_set)(struct pinctrl_dev *pctldev, unsigned
> > > > > +int
> > pin_id,
> > > > > +			       unsigned long *configs, unsigned int num_configs);
> > > > > +	void (*imx_pinctrl_parse_pin)(struct imx_pinctrl *ipctl,
> > > > > +				      unsigned int *pin_id, struct imx_pin *pin,
> > > > > +				      const __be32 **list_p);
> > > >
> > > > Compared with V4, this new implementation seems a bit complicated.
> > > > I guess we don't have to support PINCTRL_IMX=y &&
> > > > PINCTRL_IMX_SCU=m case.
> > > > Will that make the support a bit easier?
> > >
> > > I am NOT sure if such scenario meets requirement, the fact is other
> > > non-i.MX SoC also selects the PINCTRL_IMX which will make
> > > PINCTRL_IMX=y, so in that case, even all i.MX PINCTRL drivers are
> > > set to module, it will still have PINCTRL_IMX=y and
> > > PINCTRL_IMX_SCU=m, then build will fail. And I believe the auto
> > > build test may also cover such case and build error will be
> > > reported, that is why this change is needed and with this change,
> > > function is NOT impacted,
> > >
> >
> > Is it possible to add some constrainst to make sure PINCTRL_IMX_SCU
> > value is the same as PINCTRL_IMX? Or combine them into one?
> > If we can do that, it may ease the implementation a lot and make the
> > code still clean.
> 
> Combine PINCTRL_IMX_SCU and PINCTRL_IMX is NOT making sense, since for
> non-SCU platforms, PINCTRL_IMX_SCU is NOT necessary, to make
> PINCTRL_IMX_SCU same value as PINCTRL_IMX, unless make "select
> PINCTRL_IMX_SCU" in PINCTRL_IMX, but that is also NOT making sense,
> because, PINCTRL_IMX does NOT depends on PINCTRL_IMX_SCU at all.
> 

PINCTRL_IMX_SCU could be conditionally compiled. 
Something like follows:
obj-$(CONFIG_PINCTRL_IMX) += pinctrl-imx-core.o
pinctrl-imx-core-y := pinctrl-imx.o
pinctrl-imx-core-$(CONFIG_PINCTRL_IMX_SCU) += pinctrl-scu.o

Can you try if this way could work?

Regards
Aisheng

> The change is NOT that big IMO, and no better idea in my mind, have tried that
> in previous versions of patch series.
> 
> Anson