Hi,
On 08-11-16 12:52, Jacek Anaszewski wrote:
> Hi Hans,
>
> I've tested it with userspace test application and it seems to work
> well both with hardware leds-aat1290 driver and drivers/leds/uleds.c.
>
> Applied to the for-next branch of linux-leds.git.
Great, thank you. Can you also add a stable branch / tag with this
commit which the platform/x86 maintainer can merge into his tree,
so that he can merge the platform/x86 driver changes which depend
up on the new led_notify_brightness_change() function ?
Regards,
Hans
>
> Thanks,
> Jacek Anaszewski
>
> On 11/01/2016 02:37 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
>> Changes in v3:
>> -Rebase on linux-leds/for-next
>> Changes in v4:
>> -No Changes
>> ---
>> 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 491cdee..0af5191 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.
>>
>> Writing 0 to this file clears active trigger.
>>
>> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
>> index 731e4eb..c8d2d67 100644
>> --- a/drivers/leds/led-class.c
>> +++ b/drivers/leds/led-class.c
>> @@ -204,6 +204,14 @@ 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
>> @@ -255,6 +263,7 @@ 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 2d0c75a..af78279 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 52993de..f034c2d 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>
>> @@ -93,6 +94,8 @@ struct led_classdev {
>>
>> struct work_struct set_brightness_work;
>>
>> + struct kernfs_node *brightness_kn;
>> +
>> #ifdef CONFIG_LEDS_TRIGGERS
>> /* Protects the trigger data below */
>> struct rw_semaphore trigger_lock;
>> @@ -192,6 +195,15 @@ 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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