diff options
| author | Johan Hovold <johan@kernel.org> | 2015-05-04 17:10:33 +0200 |
|---|---|---|
| committer | Linus Walleij <linus.walleij@linaro.org> | 2015-05-12 10:46:53 +0200 |
| commit | 166a85e44245d771bd7042f3ad72aa0e12bb53bd (patch) | |
| tree | a9fd0409715c50ff15d2314b2314b4358c754ffb /Documentation/zh_CN | |
| parent | 426577bd8846d67b735b3a4e8926ef00abb15297 (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/zh_CN')
| -rw-r--r-- | Documentation/zh_CN/gpio.txt | 8 |
1 files changed, 0 insertions, 8 deletions
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 控制器的路径类似 /sys/class/gpio/gpiochip42/ (对于从#42 GPIO int gpio_export_link(struct device *dev, const char *name, unsigned gpio) - /* 改变 sysfs 中的一个 GPIO 节点的极性 */ - int gpio_sysfs_set_active_low(unsigned gpio, int value); - 在一个内核驱动申请一个 GPIO 之后，它可以通过 gpio_export()使其在 sysfs 接口中可见。该驱动可以控制信号方向是否可修改。这有助于防止用户空间代码无意间 破坏重要的系统状态。 @@ -651,8 +648,3 @@ GPIO 控制器的路径类似 /sys/class/gpio/gpiochip42/ (对于从#42 GPIO 在 GPIO 被导出之后，gpio_export_link()允许在 sysfs 文件系统的任何地方 创建一个到这个 GPIO sysfs 节点的符号链接。这样驱动就可以通过一个描述性的 名字，在 sysfs 中他们所拥有的设备下提供一个(到这个 GPIO sysfs 节点的)接口。 - -驱动可以使用 gpio_sysfs_set_active_low() 来在用户空间隐藏电路板之间 -GPIO 线的极性差异。这个仅对 sysfs 接口起作用。极性的改变可以在 gpio_export() -前后进行,且之前使能的轮询操作(poll(2))支持(上升或下降沿)将会被重新配置来遵循 -这个设置。 |