linux-kernel - Re: [PATCH v2 04/10] pinctrl: sunxi: Prepare for building SoC specific drivers as modules

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Date:	Tue, 19 May 2015 10:16:37 +0200
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Chen-Yu Tsai <wens@...e.org>
Cc:	Jens Kuske <jenskuske@...il.com>,
	Emilio López <emilio@...pez.com.ar>,
	Mike Turquette <mturquette@...aro.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Vishnu Patekar <vishnupatekar0510@...il.com>,
	Hans de Goede <hdegoede@...hat.com>,
	devicetree <devicetree@...r.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-sunxi <linux-sunxi@...glegroups.com>
Subject: Re: [PATCH v2 04/10] pinctrl: sunxi: Prepare for building SoC
 specific drivers as modules

On Tue, May 19, 2015 at 04:02:39PM +0800, Chen-Yu Tsai wrote:
> On Tue, May 19, 2015 at 3:55 PM, Maxime Ripard
> <maxime.ripard@...e-electrons.com> wrote:
> > On Mon, May 18, 2015 at 11:32:31AM +0200, Jens Kuske wrote:
> >> Hi,
> >>
> >> On 05/17/15 16:19, Maxime Ripard wrote:
> >> > On Fri, May 15, 2015 at 06:38:54PM +0200, Jens Kuske wrote:
> >> >> Add a remove function and export the init and remove function
> >> >> to allow us to build the SoC specific drivers as modules.
> >> >>
> >> >> Signed-off-by: Jens Kuske <jenskuske@...il.com>
> >> >> ---
> >> >>  drivers/pinctrl/sunxi/pinctrl-sunxi.c | 25 +++++++++++++++++++------
> >> >>  drivers/pinctrl/sunxi/pinctrl-sunxi.h |  2 ++
> >> >>  2 files changed, 21 insertions(+), 6 deletions(-)
> >> >>
> >> >> diff --git a/drivers/pinctrl/sunxi/pinctrl-sunxi.c b/drivers/pinctrl/sunxi/pinctrl-sunxi.c
> >> >> index f8e171b..4ef6b3d 100644
> >> >> --- a/drivers/pinctrl/sunxi/pinctrl-sunxi.c
> >> >> +++ b/drivers/pinctrl/sunxi/pinctrl-sunxi.c
> >> >> @@ -856,7 +856,6 @@ int sunxi_pinctrl_init(struct platform_device *pdev,
> >> >>    struct sunxi_pinctrl *pctl;
> >> >>    struct resource *res;
> >> >>    int i, ret, last_pin;
> >> >> -  struct clk *clk;
> >> >>
> >> >>    pctl = devm_kzalloc(&pdev->dev, sizeof(*pctl), GFP_KERNEL);
> >> >>    if (!pctl)
> >> >> @@ -954,13 +953,13 @@ int sunxi_pinctrl_init(struct platform_device *pdev,
> >> >>                    goto gpiochip_error;
> >> >>    }
> >> >>
> >> >> -  clk = devm_clk_get(&pdev->dev, NULL);
> >> >> -  if (IS_ERR(clk)) {
> >> >> -          ret = PTR_ERR(clk);
> >> >> +  pctl->clk = devm_clk_get(&pdev->dev, NULL);
> >> >> +  if (IS_ERR(pctl->clk)) {
> >> >> +          ret = PTR_ERR(pctl->clk);
> >> >>            goto gpiochip_error;
> >> >>    }
> >> >>
> >> >> -  ret = clk_prepare_enable(clk);
> >> >> +  ret = clk_prepare_enable(pctl->clk);
> >> >>    if (ret)
> >> >>            goto gpiochip_error;
> >> >>
> >> >> @@ -1015,10 +1014,24 @@ int sunxi_pinctrl_init(struct platform_device *pdev,
> >> >>    return 0;
> >> >>
> >> >>  clk_error:
> >> >> -  clk_disable_unprepare(clk);
> >> >> +  clk_disable_unprepare(pctl->clk);
> >> >>  gpiochip_error:
> >> >>    gpiochip_remove(pctl->chip);
> >> >>  pinctrl_error:
> >> >>    pinctrl_unregister(pctl->pctl_dev);
> >> >>    return ret;
> >> >>  }
> >> >> +EXPORT_SYMBOL(sunxi_pinctrl_init);
> >> >> +
> >> >> +int sunxi_pinctrl_remove(struct platform_device *pdev)
> >> >> +{
> >> >> +  struct sunxi_pinctrl *pctl = platform_get_drvdata(pdev);
> >> >> +
> >> >> +  gpiochip_remove(pctl->chip);
> >> >> +  pinctrl_unregister(pctl->pctl_dev);
> >> >> +
> >> >> +  clk_disable_unprepare(pctl->clk);
> >> >
> >> > We should also remove the domain and the interrupt mapping here.
> >>
> >> Ouch, I missed that. Only looked at the *_error: labels.
> >>
> >> Apart from that, currently the kernel panics some seconds after removing
> >> the pinctrl module because mmc wants to access a gpio. Can this be
> >> prevented somehow? I think pinctrl must not be removed once other
> >> devices use any pin-related things.
> >
> > pinctrl_unregister doesn't look like it cares about whether or not
> > there's users left in the system.
> >
> > Maybe the easiest path would be to just make this builtin like Paul
> > suggested then ... :/
> 
> Is there a way to mark modules as not removable? At least we can keep
> the multi-platform kernel image small.

If there's no module_exit, the module will only be removable through a
rmmod -f, which seems like an acceptable solution.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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