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authorJohan Hovold <johan@kernel.org>2015-05-04 17:10:33 +0200
committerLinus Walleij <linus.walleij@linaro.org>2015-05-12 10:46:53 +0200
commit166a85e44245d771bd7042f3ad72aa0e12bb53bd (patch)
treea9fd0409715c50ff15d2314b2314b4358c754ffb /Documentation/gpio
parent426577bd8846d67b735b3a4e8926ef00abb15297 (diff)
gpio: remove gpiod_sysfs_set_active_low
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@lwn.net> Cc: Harry Wei <harryxiyou@gmail.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: linux-doc@vger.kernel.org Cc: linux-kernel@zh-kernel.org Cc: linux-arch@vger.kernel.org Signed-off-by: Johan Hovold <johan@kernel.org> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'Documentation/gpio')
-rw-r--r--Documentation/gpio/gpio-legacy.txt9
-rw-r--r--Documentation/gpio/sysfs.txt8
2 files changed, 0 insertions, 17 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.