From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Garrett Subject: Re: [PATCH] backlight: add support for disabling backlights via sysfs Date: Thu, 28 Jun 2012 20:10:43 +0100 Message-ID: <20120628191043.GA9777@srcf.ucam.org> References: <1340910426-13269-1-git-send-email-seth.forshee@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from cavan.codon.org.uk ([93.93.128.6]:52128 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752207Ab2F1TKq (ORCPT ); Thu, 28 Jun 2012 15:10:46 -0400 Content-Disposition: inline In-Reply-To: <1340910426-13269-1-git-send-email-seth.forshee@canonical.com> Sender: platform-driver-x86-owner@vger.kernel.org List-ID: To: Seth Forshee Cc: Richard Purdie , linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org, Corentin Chary On Thu, Jun 28, 2012 at 02:07:06PM -0500, Seth Forshee wrote: > Rather than trying to address this situation in a piecemeal fashion, we > should find a solution that deal with disabling broken backlights more > generically. This patch does so by adding an "enabled" attribute to > sysfs for backlight devices. Writing 0 to this attribute disables the > backlight, blocking most attempts to change the state. Tools like udev > can set use this attribute to disable known broken backlight interfaces, > and tools like gnome-settings-daemon can query the attribute to avoid > using disabled backlights. I'm not entirely thrilled by this, especially because in several cases I suspect that we're just going to end up disabling acpi_backlight rather than fixing any of the range of integration bugs we still have with it. If anyone has links with OEMs then I'd love to know how Windows handles backlight control policy, but otherwise I think Corentin's approach of having the vendor drivers promote or demote themselves makes more sense than pushing the problem out to userspace. -- Matthew Garrett | mjg59@srcf.ucam.org