From 166a85e44245d771bd7042f3ad72aa0e12bb53bd Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Mon, 4 May 2015 17:10:33 +0200 Subject: 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 Cc: Harry Wei Cc: Arnd Bergmann Cc: linux-doc@vger.kernel.org Cc: linux-kernel@zh-kernel.org Cc: linux-arch@vger.kernel.org Signed-off-by: Johan Hovold Reviewed-by: Alexandre Courbot Signed-off-by: Linus Walleij --- Documentation/zh_CN/gpio.txt | 8 -------- 1 file changed, 8 deletions(-) (limited to 'Documentation/zh_CN/gpio.txt') 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。 -- cgit v1.2.3