linux-kernel - Re: [PATCH] pinctrl: baytrail: show output gpio state correctly on Intel Baytrail

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Date:	Fri, 31 Oct 2014 08:20:05 -0500
From:	Felipe Balbi <balbi@...com>
To:	Linus Walleij <linus.walleij@...aro.org>
CC:	Felipe Balbi <balbi@...com>,
	David Cohen <david.a.cohen@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	stable <stable@...r.kernel.org>
Subject: Re: [PATCH] pinctrl: baytrail: show output gpio state correctly on
 Intel Baytrail

Hi,

On Fri, Oct 31, 2014 at 09:12:16AM +0100, Linus Walleij wrote:
> On Tue, Oct 28, 2014 at 3:42 PM, Felipe Balbi <balbi@...com> wrote:
> > On Tue, Oct 28, 2014 at 11:15:20AM +0100, Linus Walleij wrote:
> >> On Mon, Oct 13, 2014 at 9:36 PM, Felipe Balbi <balbi@...com> wrote:
> >> > On Mon, Oct 13, 2014 at 02:26:32PM -0500, Felipe Balbi wrote:
> >>
> >> > I also noticed that this is missing:
> >> >
> >> > diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/pinctrl-baytrail.c
> >> > index e12e5b0..7db5ab9 100644
> >> > --- a/drivers/pinctrl/pinctrl-baytrail.c
> >> > +++ b/drivers/pinctrl/pinctrl-baytrail.c
> >> > @@ -614,3 +614,9 @@ static int __init byt_gpio_init(void)
> >> >  }
> >> >
> >> >  subsys_initcall(byt_gpio_init);
> >> > +
> >> > +static void __exit byt_gpio_exit(void)
> >> > +{
> >> > +       platform_driver_unregister(&byt_gpio_driver);
> >> > +}
> >> > +module_exit(byt_gpio_exit);
> >>
> >> But the Baytrail driver is not a loadable module, it is bool:
> >>
> >> config PINCTRL_BAYTRAIL
> >>         bool "Intel Baytrail GPIO pin control"
> >>         depends on GPIOLIB && ACPI && X86
> >>
> >> (...)
> >>
> >> So I guess it won't need handling for removal, as it can only
> >> be compiled-in.
> >
> > you can still unbind it through sysfs, right ? The thing also already
> > provides a ->remove() method anyway.
> 
> Yes you're right of course...
> 
> But another way to get rid of the dilemma is to set
> .suppress_bind_attrs = true on the .driver field of the
> device driver. The one can't unbind it through sysfs anymore.
> 
>         .driver = {
>                 .name   = "foo",
>                 .suppress_bind_attrs = true,
>         },
> 
> So one of them need to be done.
> 
> I suspect this is a kind of common problem...

so instead of taking of taking a three-liner which just makes sure this
can be used as "intended" you prefer to:

diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/pinctrl-baytrail.c
index e12e5b0..254ba81 100644
--- a/drivers/pinctrl/pinctrl-baytrail.c
+++ b/drivers/pinctrl/pinctrl-baytrail.c
@@ -587,16 +587,6 @@ static const struct acpi_device_id byt_gpio_acpi_match[] = {
 };
 MODULE_DEVICE_TABLE(acpi, byt_gpio_acpi_match);
 
-static int byt_gpio_remove(struct platform_device *pdev)
-{
-	struct byt_gpio *vg = platform_get_drvdata(pdev);
-
-	pm_runtime_disable(&pdev->dev);
-	gpiochip_remove(&vg->chip);
-
-	return 0;
-}
-
 static struct platform_driver byt_gpio_driver = {
 	.probe          = byt_gpio_probe,
 	.remove         = byt_gpio_remove,
@@ -605,6 +595,7 @@ static struct platform_driver byt_gpio_driver = {
 		.owner  = THIS_MODULE,
 		.pm	= &byt_gpio_pm_ops,
 		.acpi_match_table = ACPI_PTR(byt_gpio_acpi_match),
+		.suppress_bind_attrs = true,
 	},
 };
 

I don't quite care since this is not an architecture I work for, but I
prefer drivers which can be unbound one way or another. Not to mention
that there's already a ->remove callback on the platform_driver anyway.

-- 
balbi

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