From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Garrett Date: Sun, 24 Nov 2013 01:02:57 +0000 Subject: Re: [ibm-acpi-devel] [PATCH] video: backlight: Remove backlight sysfs uevent Message-Id: <20131124010257.GA6376@srcf.ucam.org> List-Id: 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> In-Reply-To: <20131124004015.GA19499@khazad-dum.debian.net> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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' 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