linux-kernel - Re: [PATCH] i915: Quirk out disconnected backlight

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Message-ID: <20120914144049.GB8195@srcf.ucam.org>
Date:	Fri, 14 Sep 2012 15:40:49 +0100
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	David Woodhouse <dwmw2@...radead.org>
Cc:	Grant Likely <grant.likely@...retlab.ca>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	David Airlie <airlied@...ux.ie>
Subject: Re: [PATCH] i915: Quirk out disconnected backlight

On Fri, Sep 14, 2012 at 03:29:14PM +0100, David Woodhouse wrote:
> On Fri, 2012-09-14 at 14:48 +0100, Matthew Garrett wrote:
> > On Fri, Sep 14, 2012 at 01:57:06PM +0100, Grant Likely wrote:
> > 
> > > Tested on MacbookPro8,3. Without this patch both the intel_backlight and
> > > gmux_backlight devices get registered and userspace doesn't know which
> > > it should use.
> > 
> > Userspace should be figuring out which one to use from the type field.
> 
> It only does that if it's using gsd-backlight-helper to poke
> at /sys/class/backlight directly. If X exposes a backlight, (as it does
> for the Intel backlight), then gsd will just use that.

Yeah, X should be doing the same. If it's not then it's broken. OTOH, I 
do agree that if we already know that we can't do anything with the 
backlight (as is clearly the case if the PWM field is 0) we should just 
disable it.

-- 
Matthew Garrett | mjg59@...f.ucam.org
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