Hi, On 24-10-16 22:43, Jacek Anaszewski wrote:
Hi Hans, Thanks for the update. Could you please rebase your patches onto recent linux-leds.git, for-next branch?
Done, I will send a v3 soon (today or tomorrow).
Also it would be convenient to have sample application for polling brightness changes in tools/leds.
I'm sorry but I do not have time to create such a sample application. Regards, Hans
Thanks, Jacek Anaszewski On 10/23/2016 09:46 PM, Hans de Goede wrote:Add support for userspace using poll() for POLL_PRI on the sysfs brightness attr to watch for brightness changes. This commit adds a led_notify_brightness_change helper function for waking up any poll() waiters; and calls this after any brightness changes (after any led_classdev->brightness_set[_blocking] calls have completed). In some use-cases led hardware may autonomously change its brightness, e.g. the keyboard backlight used on some laptops is controlled by a hardwired (firmware handled) hotkey. led_notify_brightness_change is exported for use by drivers which can detect such autonomous changes. This commit also updates the Documentation/ABI/testing/sysfs-class-led documentation to document that userspace may now poll on the brightness attribute. Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> --- Changes in v2: -Wakeup / notify userspace on any brightness changes, not just on autonomous changes done by the hw --- Documentation/ABI/testing/sysfs-class-led | 8 ++++++-- drivers/leds/led-class.c | 9 +++++++++ drivers/leds/led-core.c | 16 +++++++++++++++- include/linux/leds.h | 12 ++++++++++++ 4 files changed, 42 insertions(+), 3 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentation/ABI/testing/sysfs-class-led index 86ace28..0685551 100644 --- a/Documentation/ABI/testing/sysfs-class-led +++ b/Documentation/ABI/testing/sysfs-class-led @@ -1,12 +1,16 @@ What: /sys/class/leds/<led>/brightness -Date: March 2006 -KernelVersion: 2.6.17 +Date: March 2006 (poll October 2016) +KernelVersion: 2.6.17 (poll since 4.10) Contact: Richard Purdie <rpurdie@xxxxxxxxx> Description: Set the brightness of the LED. Most LEDs don't have hardware brightness support so will just be turned on for non-zero brightness settings. The value is between 0 and /sys/class/leds/<led>/max_brightness. + The file supports poll() to detect brightness changes, in + some cases the hardware / firmware may change the brightness + autonomously, poll() should be woken up in this case too, + but not all drivers may support this. What: /sys/class/leds/<led>/max_brightness Date: March 2006 diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c index aa84e5b..3427a65 100644 --- a/drivers/leds/led-class.c +++ b/drivers/leds/led-class.c @@ -203,6 +203,14 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev) dev_warn(parent, "Led %s renamed to %s due to name collision", led_cdev->name, dev_name(led_cdev->dev)); + led_cdev->brightness_kn = sysfs_get_dirent(led_cdev->dev->kobj.sd, + "brightness"); + if (!led_cdev->brightness_kn) { + dev_err(led_cdev->dev, "Error getting brightness kernfs_node\n"); + device_unregister(led_cdev->dev); + return -ENODEV; + } + #ifdef CONFIG_LEDS_TRIGGERS init_rwsem(&led_cdev->trigger_lock); #endif @@ -254,6 +262,7 @@ void led_classdev_unregister(struct led_classdev *led_cdev) flush_work(&led_cdev->set_brightness_work); + sysfs_put(led_cdev->brightness_kn); device_unregister(led_cdev->dev); down_write(&leds_list_lock); diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c index 3bce448..e2e5cc7 100644 --- a/drivers/leds/led-core.c +++ b/drivers/leds/led-core.c @@ -33,16 +33,24 @@ static int __led_set_brightness(struct led_classdev *led_cdev, led_cdev->brightness_set(led_cdev, value); + led_notify_brightness_change(led_cdev); + return 0; } static int __led_set_brightness_blocking(struct led_classdev *led_cdev, enum led_brightness value) { + int ret; + if (!led_cdev->brightness_set_blocking) return -ENOTSUPP; - return led_cdev->brightness_set_blocking(led_cdev, value); + ret = led_cdev->brightness_set_blocking(led_cdev, value); + if (ret >= 0) + led_notify_brightness_change(led_cdev); + + return ret; } static void led_timer_function(unsigned long data) @@ -308,6 +316,12 @@ int led_update_brightness(struct led_classdev *led_cdev) } EXPORT_SYMBOL_GPL(led_update_brightness); +void led_notify_brightness_change(struct led_classdev *led_cdev) +{ + sysfs_notify_dirent(led_cdev->brightness_kn); +} +EXPORT_SYMBOL_GPL(led_notify_brightness_change); + /* Caller must ensure led_cdev->led_access held */ void led_sysfs_disable(struct led_classdev *led_cdev) { diff --git a/include/linux/leds.h b/include/linux/leds.h index ddfcb2d..eebcd8c 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -13,6 +13,7 @@ #define __LINUX_LEDS_H_INCLUDED #include <linux/device.h> +#include <linux/kernfs.h> #include <linux/list.h> #include <linux/mutex.h> #include <linux/rwsem.h> @@ -94,6 +95,8 @@ struct led_classdev { struct work_struct set_brightness_work; int delayed_set_value; + struct kernfs_node *brightness_kn; + #ifdef CONFIG_LEDS_TRIGGERS /* Protects the trigger data below */ struct rw_semaphore trigger_lock; @@ -193,6 +196,15 @@ extern int led_set_brightness_sync(struct led_classdev *led_cdev, extern int led_update_brightness(struct led_classdev *led_cdev); /** + * led_notify_brightness_change - Notify userspace of brightness changes + * @led_cdev: the LED to do the notify on + * + * Let any users waiting for POLL_PRI on the led's brightness sysfs + * atrribute know that the brightness has been changed. + */ +extern void led_notify_brightness_change(struct led_classdev *led_cdev); + +/** * led_sysfs_disable - disable LED sysfs interface * @led_cdev: the LED to set *
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