RE: [PATCH 1/3] gpio: mxc: Support module build

From: Anson Huang <anson.huang@nxp.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Will Deacon <will@kernel.org>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Shawn Guo <shawnguo@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Olof Johansson <olof@lixom.net>,
	Russell King <linux@armlinux.org.uk>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	"oleksandr.suvorov@toradex.com" <oleksandr.suvorov@toradex.com>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Vinod Koul <vkoul@kernel.org>,
	Andreas Kemnade <andreas@kemnade.info>,
	dl-linux-imx <linux-imx@nxp.com>,
	Sascha Hauer <kernel@pengutronix.de>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Adam Ford <aford173@gmail.com>, Leo Li <leoyang.li@nxp.com>,
	Fabio Estevam <festevam@gmail.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	"hverkuil-cisco@xs4all.nl" <hverkuil-cisco@xs4all.nl>
Subject: RE: [PATCH 1/3] gpio: mxc: Support module build
Date: Wed, 15 Jul 2020 02:44:00 +0000	[thread overview]
Message-ID: <DB3PR0402MB3916FB27846F462C2210C3BFF57E0@DB3PR0402MB3916.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <DB3PR0402MB39168FEA9306CBF90A596E31F5630@DB3PR0402MB3916.eurprd04.prod.outlook.com>

Hi, Linus

> Subject: RE: [PATCH 1/3] gpio: mxc: Support module build
> 
> Hi, Linus
> 
> > Subject: Re: [PATCH 1/3] gpio: mxc: Support module build
> >
> > On Wed, Jul 8, 2020 at 1:28 AM Anson Huang <Anson.Huang@nxp.com>
> > wrote:
> >
> > >  subsys_initcall(gpio_mxc_init);
> > > +
> > > +MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
> > > +MODULE_DESCRIPTION("i.MX GPIO Driver"); MODULE_LICENSE("GPL");
> >
> > You are making this modualrizable but keeping the subsys_initcall(),
> > which doesn't make very much sense. It is obviously not necessary to
> > do this probe at subsys_initcall() time, right?
> >
> 
> If building it as module, the subsys_initcall() will be equal to module_init(), I
> keep it unchanged is because I try to make it identical when built-in, since
> most of the config will still have it built-in, except the Android GKI support.
> Does it make sense?
> 
> > Take this opportunity to convert the driver to use
> > module_platform_driver() as well.
> 
> If you think it has to be or it is better to use module_platform_driver(), I will do
> it in V2.

I tried to replace the subsys_initcall() with module_platform_driver(), but met issue
about " register_syscore_ops(&mxc_gpio_syscore_ops);" which is called in gpio_mxc_init()
function, this function should be called ONLY once, moving it to .probe function is NOT
working, so we may need to keep the gpio_mxc_init(), that is another reason that we may
need to keep subsys_initcall()?

Thanks,
Anson
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