From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Skeggs Subject: Re: nouveau exposes backlight controls in presence of ACPI Date: Wed, 03 Nov 2010 08:37:51 +1000 Message-ID: <1288737471.6100.0.camel@nisroch> References: <20101029154934.GA2076@aeneby.se> <1288670315.6477.2.camel@nisroch> <20101102145153.GA4075@aeneby.se> Reply-To: skeggsb-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20101102145153.GA4075-+1tCnOwpXBmzQB+pC5nmwQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: nouveau-bounces+gcfxn-nouveau=m.gmane.org-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org Errors-To: nouveau-bounces+gcfxn-nouveau=m.gmane.org-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org To: Aaron Sowry Cc: nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org List-Id: nouveau.vger.kernel.org On Tue, 2010-11-02 at 15:51 +0100, Aaron Sowry wrote: > > However. There's also the platform-specific modules (thinkpad etc) that > > will provide their own backlight methods if the standard ACPI mechanism > > isn't available. I didn't see any immediately obvious way of knowing > > whether or not they were being provided. > > > > I'm not too certain the best way to deal with this, any ideas? :) > > See attached patch, which prevents nouveau registering a backlight control if ACPI already provides one. If there are no glaring errors in the code/implementation then I would like to submit it. This is much like what I intended to commit. I guess it doesn't hurt to do so, it doesn't help with all cases yet but if it fixes issues for some people, why not. Ben. > > Dealing with platform-specific modules is tricky because it looks like nouveau initialises itself quite early on in the boot process: > > [aaron@jules ~]$ dmesg | grep ACPI > ... > [ 3.359377] nouveau 0000:01:00.0: power state changed by ACPI to D0 > [ 3.359560] nouveau 0000:01:00.0: power state changed by ACPI to D0 > [ 4.860678] [drm] nouveau 0000:01:00.0: Detected ACPI backlight support, not registering control > [ 14.206997] ACPI: WMI: Skipping duplicate GUID 05901221-D566-11D1-B2F0-00A0C9062910 > [ 14.207693] ACPI: WMI: Mapper loaded > [ 17.686907] thinkpad_acpi: ThinkPad ACPI Extras v0.24 > [ 17.689517] thinkpad_acpi: This ThinkPad has standard ACPI backlight brightness control, supported by the ACPI video driver > [ 17.756039] thinkpad_acpi: Standard ACPI backlight interface available, not loading native one. > > My suggestion would be that it is the responsibility of user-space to select an appropriate ACPI backlight control. > > /Aaron