On Wed, Dec 24, 2014 at 12:06 PM, Pali Rohár <pali.rohar@xxxxxxxxx> wrote: > Hello! > > What is preferred way from kernel driver to inform userspace > about LED device brightness change? In /sys/class/leds/<device>/ > is file brightness which can be used to read current brightness > or set write new value. But sometimes also firmware (or device) > can change value on its own and thus userspace software which > provides slider for setting brightness will be incorrect. > > For example on Dell laptops there is driver which support setting > and reading keyboard backlight (via leds kernel interface). But > firmware/BIOS can change brightness (when something happen) and > it can inform running system about this change via ACPI/WMI event > interface. But how to use kernel led interface to inform userpace > about this change? It is possible? > Sorry for the delay, actually I don't find any possible existing way to send brightness change event from LED subsystem to user space. I think we can add an udev event in set_brightness API, then when we change the brightness, it will send out udev event to user space. Thanks, -Bryan -- To unsubscribe from this list: send the line "unsubscribe linux-leds" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
