From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756393Ab3KXBDM (ORCPT ); Sat, 23 Nov 2013 20:03:12 -0500 Received: from cavan.codon.org.uk ([93.93.128.6]:34978 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755708Ab3KXBDH (ORCPT ); Sat, 23 Nov 2013 20:03:07 -0500 Date: Sun, 24 Nov 2013 01:02:57 +0000 From: Matthew Garrett To: Henrique de Moraes Holschuh Cc: linux-fbdev@vger.kernel.org, "'Kyungmin Park'" , kay@vrfy.org, Jingoo Han , "'Henrique de Moraes Holschuh'" , linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org, ibm-acpi-devel@lists.sourceforge.net, "'Richard Purdie'" Subject: Re: [ibm-acpi-devel] [PATCH] video: backlight: Remove backlight sysfs uevent Message-ID: <20131124010257.GA6376@srcf.ucam.org> References: <20131111235700.GA29987@july> <002901cedf3c$a7e77a00$f7b66e00$%han@samsung.com> <20131112005628.GA2914@khazad-dum.debian.net> <1384990859.20536.4.camel@x230> <20131121114332.GA23710@khazad-dum.debian.net> <20131121143326.GA19773@srcf.ucam.org> <20131122113601.GB27196@khazad-dum.debian.net> <20131122171556.GA15680@srcf.ucam.org> <20131124004015.GA19499@khazad-dum.debian.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131124004015.GA19499@khazad-dum.debian.net> User-Agent: Mutt/1.5.20 (2009-06-14) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: mjg59@cavan.codon.org.uk X-SA-Exim-Scanned: No (on cavan.codon.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Nov 23, 2013 at 10:40:15PM -0200, Henrique de Moraes Holschuh wrote: > On Fri, 22 Nov 2013, Matthew Garrett wrote: > > We have userspace that relies on uevents of type > > BACKLIGHT_UPDATE_HOTKEY. I don't know that we have userspace that relies > > on uevents of type BACKLIGHT_UPDATE_SYSFS. > > Any OSD application would have to rely on both uevent types, or it is broken > (and to test that, just write a level to sysfs and watch the OSD app fail to > tell you about the backlight level change...) Right, OSDs are supposed to respond to keypresses, not arbitrary changes of backlight. If the user's just echoed 8 into brightness, they know they set the brightness to 8 - they don't need an OSD to tell them that. BACKLIGHT_UPDATE_HOTKEY is when the firmware itself has changed the brightness in response to a keypress, and so reporting the keypress would result in additional backlight changes. -- Matthew Garrett | mjg59@srcf.ucam.org