linux-kernel - Re: [PATCH 05/21] x86/platform: select legacy gpiolib interfaces where used

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Message-ID: <npijagtgyad33xxlq46b7kwzydhcgt5tkgd5ihsjl6t4czbqyf@umovipwh73i2>
Date: Sun, 10 Aug 2025 19:27:22 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Hans de Goede <hansg@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>, 
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Arnd Bergmann <arnd@...nel.org>, 
	Bartosz Golaszewski <brgl@...ev.pl>, Linus Walleij <linus.walleij@...aro.org>, 
	"open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>, Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>, 
	Lee Jones <lee@...nel.org>, Dzmitry Sankouski <dsankouski@...il.com>, 
	Heiko Stübner <heiko@...ech.de>, linux <linux@...blig.org>, 
	Thomas Weißschuh <linux@...ssschuh.net>, Guenter Roeck <linux@...ck-us.net>, linux-input@...r.kernel.org, 
	linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH 05/21] x86/platform: select legacy gpiolib interfaces
 where used

Hi Hans,

On Sun, Aug 10, 2025 at 05:12:46PM +0200, Hans de Goede wrote:
> Hi Arnd, Andy,
> 
> On 9-Aug-25 9:44 PM, Arnd Bergmann wrote:
> > On Sat, Aug 9, 2025, at 12:00, Andy Shevchenko wrote:
> >> On Fri, Aug 08, 2025 at 05:17:49PM +0200, Arnd Bergmann wrote:
> >>> From: Arnd Bergmann <arnd@...db.de>
> >>>
> >>> A few old machines have not been converted away from the old-style
> >>> gpiolib interfaces. Make these select the new CONFIG_GPIOLIB_LEGACY
> >>> symbol so the code still works where it is needed but can be left
> >>> out otherwise.
> >>
> >>> --- a/drivers/platform/x86/x86-android-tablets/Kconfig
> >>> +++ b/drivers/platform/x86/x86-android-tablets/Kconfig
> >>> @@ -8,6 +8,7 @@ config X86_ANDROID_TABLETS
> >>>  	depends on I2C && SPI && SERIAL_DEV_BUS
> >>>  	depends on GPIOLIB && PMIC_OPREGION
> >>>  	depends on ACPI && EFI && PCI
> >>> +	select GPIOLIB_LEGACY
> >>>  	select NEW_LEDS
> >>>  	select LEDS_CLASS
> >>>  	select POWER_SUPPLY
> >>
> >> Hmm... This is a surprising change. But I leave it to Hans.
> 
> Yes I was surprised by this myself since I explicitly removed
> all legacy GPIO use from the x86-android-tablets code a while
> ago (or so I thought).
> 
> > I think the only function that still needs it is
> > x86_android_tablet_probe() doing
> > 
> > static struct gpio_keys_button *buttons;
> > 
> >                 for (i = 0; i < dev_info->gpio_button_count; i++) {
> >                         ret = x86_android_tablet_get_gpiod(dev_info->gpio_button[i].chip,
> >                                                            dev_info->gpio_button[i].pin,
> >                                                            dev_info->gpio_button[i].button.desc,
> >                                                            false, GPIOD_IN, &gpiod);
> > 
> >                         buttons[i] = dev_info->gpio_button[i].button;
> >                         buttons[i].gpio = desc_to_gpio(gpiod);
> >                         /* Release GPIO descriptor so that gpio-keys can request it */
> >                         devm_gpiod_put(&x86_android_tablet_device->dev, gpiod);
> >                 }
> > 
> > So the driver itself uses gpio descriptors, but it passes
> > some of them into another driver by number. There is probably
> > an easy workaround that I did not see.
> 
> Ah I see, so this is basically in the same boat as
> drivers/input/misc/soc_button_array.c which also first
> gets a gpio_desc and then calls desc_to_gpio() to store
> the GPIO number in struct gpio_keys_button which is passed
> as platform_data to drivers/input/keyboard/gpio_keys.c
> 
> The gpio_keys driver then converts things back
> into a gpio_desc in gpio_keys_setup_key()
> using devm_gpio_request_one() + gpio_to_desc()
> 
> So it looks like we need to add a gpiod member to
> struct gpio_keys_button (include/linux/gpio_keys.h)
> and modify gpio_keys.c to prefer that over using
> button->gpio, something like the attached patch
> basically.
> 
> I won't have time to work on this until September,
> so if someone wants to take the attached patch and run
> with it go for it.
> 
> Note the x86-android-tablets / soc_button_array code
> will become responsible for requesting / releasing
> the gpiod when using the new gpio_keys_button.gpiod
> member.
> 
> For the x86-android-tablets code this is easy, just drop
> these 2 lines:
> 
>                         /* Release GPIO descriptor so that gpio-keys can request it */
>                         devm_gpiod_put(&x86_android_tablet_device->dev, gpiod);
> 
> And for soc_button_array.c it is _probably_ just a matter
> of switching to devm_gpiod_get_index() and drop the
> gpiod_put().
> 
> I have hardware to test both the x86-android-tablets
> code as well as the soc_button_array code. I might be
> able to do a quick test on August 22nd or 29th.

I just sent out a v2 of my series from '23 converting
x86-android-tablets to use PROPERTY_ENTRY_GPIO(), including converting
buttons and switches:


https://lore.kernel.org/all/20250810-x86-andoroid-tablet-v2-0-9c7a1b3c32b2@gmail.com/

I do not have hardware so it probably is busted but if you could make it
work that would be great.

Thanks.

-- 
Dmitry