Re: [PATCH 08/23] gpio: remove gpiod_sysfs_set_active_low

From: Alexandre Courbot
Date: Sun Apr 26 2015 - 23:54:45 EST

On Wed, Apr 22, 2015 at 12:42 AM, Johan Hovold <johan@xxxxxxxxxx> wrote:
> Remove gpiod_sysfs_set_active_low (and gpio_sysfs_set_active_low) which
> allowed code to change the polarity of a gpio line even after it had
> been exported through sysfs.
>
> Drivers should not care, and generally does not know, about gpio-line
> polarity which is a hardware feature that needs to be described by
> firmware.
>
> It is currently possible to define gpio-line polarity in device-tree and
> acpi firmware or using platform data. Userspace can also change the
> polarity through sysfs.
>
> Note that drivers using the legacy gpio interface could still use
> GPIOF_ACTIVE_LOW to change the polarity before exporting the gpio.
>
> There are no in-kernel users of this interface.
>
> Cc: Jonathan Corbet <corbet@xxxxxxx>
> Cc: Harry Wei <harryxiyou@xxxxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>
> Cc: linux-doc@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxx
> Cc: linux-arch@xxxxxxxxxxxxxxx
> Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
> ---
> Documentation/gpio/gpio-legacy.txt | 9 -------
> Documentation/gpio/sysfs.txt | 8 -------
> Documentation/zh_CN/gpio.txt | 8 -------
> drivers/gpio/gpiolib-sysfs.c | 48 ++------------------------------------
> include/asm-generic/gpio.h | 5 ----
> include/linux/gpio.h | 7 ------
> include/linux/gpio/consumer.h | 6 -----
> 7 files changed, 2 insertions(+), 89 deletions(-)
>
> diff --git a/Documentation/gpio/gpio-legacy.txt b/Documentation/gpio/gpio-legacy.txt
> index 6f83fa965b4b..79ab5648d69b 100644
> --- a/Documentation/gpio/gpio-legacy.txt
> +++ b/Documentation/gpio/gpio-legacy.txt
> @@ -751,9 +751,6 @@ requested using gpio_request():
> int gpio_export_link(struct device *dev, const char *name,
> unsigned gpio)
>
> - /* change the polarity of a GPIO node in sysfs */
> - int gpio_sysfs_set_active_low(unsigned gpio, int value);
> -
> After a kernel driver requests a GPIO, it may only be made available in
> the sysfs interface by gpio_export(). The driver can control whether the
> signal direction may change. This helps drivers prevent userspace code
> @@ -767,9 +764,3 @@ After the GPIO has been exported, gpio_export_link() allows creating
> symlinks from elsewhere in sysfs to the GPIO sysfs node. Drivers can
> use this to provide the interface under their own device in sysfs with
> a descriptive name.
> -
> -Drivers can use gpio_sysfs_set_active_low() to hide GPIO line polarity
> -differences between boards from user space. This only affects the
> -sysfs interface. Polarity change can be done both before and after
> -gpio_export(), and previously enabled poll(2) support for either
> -rising or falling edge will be reconfigured to follow this setting.
> diff --git a/Documentation/gpio/sysfs.txt b/Documentation/gpio/sysfs.txt
> index c2c3a97f8ff7..535b6a8a7a7c 100644
> --- a/Documentation/gpio/sysfs.txt
> +++ b/Documentation/gpio/sysfs.txt
> @@ -132,9 +132,6 @@ requested using gpio_request():
> int gpiod_export_link(struct device *dev, const char *name,
> struct gpio_desc *desc);
>
> - /* change the polarity of a GPIO node in sysfs */
> - int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value);
> -
> After a kernel driver requests a GPIO, it may only be made available in
> the sysfs interface by gpiod_export(). The driver can control whether the
> signal direction may change. This helps drivers prevent userspace code
> @@ -148,8 +145,3 @@ After the GPIO has been exported, gpiod_export_link() allows creating
> symlinks from elsewhere in sysfs to the GPIO sysfs node. Drivers can
> use this to provide the interface under their own device in sysfs with
> a descriptive name.
> -
> -Drivers can use gpiod_sysfs_set_active_low() to hide GPIO line polarity
> -differences between boards from user space. Polarity change can be done both
> -before and after gpiod_export(), and previously enabled poll(2) support for
> -either rising or falling edge will be reconfigured to follow this setting.
> diff --git a/Documentation/zh_CN/gpio.txt b/Documentation/zh_CN/gpio.txt
> index d5b8f01833f4..bce972521065 100644
> --- a/Documentation/zh_CN/gpio.txt
> +++ b/Documentation/zh_CN/gpio.txt
> @@ -638,9 +638,6 @@ GPIO æååçèåçä /sys/class/gpio/gpiochip42/ (åää#42 GPIO
> int gpio_export_link(struct device *dev, const char *name,
> unsigned gpio)
>
> - /* æå sysfs äçää GPIO èççææ */
> - int gpio_sysfs_set_active_low(unsigned gpio, int value);
> -
> åääåæéåçèää GPIO äåïååäéè gpio_export()äåå sysfs
> æåäåèãèéååäæåäåæåæååäæãèæåäéæçæçéäçææé
> çåéèççççæã
> @@ -651,8 +648,3 @@ GPIO æååçèåçä /sys/class/gpio/gpiochip42/ (åää#42 GPIO
> å GPIO èååäåïgpio_export_link()åèå sysfs æäçççääåæ
> ååääåèä GPIO sysfs èçççåéæãèæéåååäéèääæèæç
> ååïå sysfs äääæææçèåäæäää(åèä GPIO sysfs èçç)æåã
> -
> -éååääç gpio_sysfs_set_active_low() æåçæçééèçèæäé
> -GPIO ççææååãèääå sysfs æåèäçãææçæååäå gpio_export()
> -ååèè,ääåäèçèèæä(poll(2))ææ(äåæäéæ)åäèéæéçæéå
> -èäèçã
> diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
> index 31434c5a90ef..8a95a954f514 100644
> --- a/drivers/gpio/gpiolib-sysfs.c
> +++ b/drivers/gpio/gpiolib-sysfs.c
> @@ -293,8 +293,8 @@ static int sysfs_set_active_low(struct gpio_desc *desc, struct device *dev,
> clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
>
> /* reconfigure poll(2) support if enabled on one edge only */
> - if (dev != NULL && (!!test_bit(FLAG_TRIG_RISE, &desc->flags) ^
> - !!test_bit(FLAG_TRIG_FALL, &desc->flags))) {
> + if (!!test_bit(FLAG_TRIG_RISE, &desc->flags) ^
> + !!test_bit(FLAG_TRIG_FALL, &desc->flags)) {

This change seems to be unrelated to this patch...

Otherwise, I agree and good riddance!
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