From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751590AbaLXUGQ (ORCPT ); Wed, 24 Dec 2014 15:06:16 -0500 Received: from mail-wg0-f42.google.com ([74.125.82.42]:64504 "EHLO mail-wg0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751398AbaLXUGO (ORCPT ); Wed, 24 Dec 2014 15:06:14 -0500 From: Pali =?utf-8?q?Roh=C3=A1r?= To: Bryan Wu , Richard Purdie , Darren Hart , linux-leds@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org Subject: LED: inform userspace about brightness change Date: Wed, 24 Dec 2014 21:06:09 +0100 User-Agent: KMail/1.13.7 (Linux/3.19.0-031900rc1-generic; KDE/4.14.2; x86_64; ; ) MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart3483831.VSxtC1L7b9"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Message-Id: <201412242106.09959@pali> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --nextPart3483831.VSxtC1L7b9 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Hello! What is preferred way from kernel driver to inform userspace=20 about LED device brightness change? In /sys/class/leds//=20 is file brightness which can be used to read current brightness=20 or set write new value. But sometimes also firmware (or device)=20 can change value on its own and thus userspace software which=20 provides slider for setting brightness will be incorrect. =46or example on Dell laptops there is driver which support setting=20 and reading keyboard backlight (via leds kernel interface). But=20 firmware/BIOS can change brightness (when something happen) and=20 it can inform running system about this change via ACPI/WMI event=20 interface. But how to use kernel led interface to inform userpace=20 about this change? It is possible? =2D-=20 Pali Roh=C3=A1r pali.rohar@gmail.com --nextPart3483831.VSxtC1L7b9 Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iEYEABECAAYFAlSbHLEACgkQi/DJPQPkQ1I1KwCgox/WYS4Cp0BuOqyXnZRHUUux 8yIAnjVdqZplFgg/LB9PSIhimxCTWaK+ =cQSp -----END PGP SIGNATURE----- --nextPart3483831.VSxtC1L7b9--