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From: Matthew Garrett <mjg59@srcf.ucam.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Alan Cox <alan@linux.jf.intel.com>,
	greg@kroah.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/5] gma500: backlight warning
Date: Wed, 13 Apr 2011 14:23:47 +0100	[thread overview]
Message-ID: <20110413132347.GA27007@srcf.ucam.org> (raw)
In-Reply-To: <20110413142022.56ebe93f@lxorguk.ukuu.org.uk>

On Wed, Apr 13, 2011 at 02:20:22PM +0100, Alan Cox wrote:
> On Wed, 13 Apr 2011 14:17:14 +0100
> Matthew Garrett <mjg59@srcf.ucam.org> wrote:
> 
> > On Wed, Apr 13, 2011 at 10:36:19AM +0100, Alan Cox wrote:
> > >  	props.max_brightness = 100;
> > > +	props.type = BACKLIGHT_PLATFORM;
> > 
> > No, this should be BACKLIGHT_RAW - it's hitting the control registers 
> > directly rather than going via a platform interface.
> 
> Ah ok - I figured it *was* the platform backlight. I'll send Greg a new
> version of that changeset.

Platform is intended for cases where the platform (ie, the specific 
instance of a GMA500-based system) provides its own mechanism, rather 
than falling through to the raw register access. The idea is that 
platform interfaces may keep track of other platform-level policy such 
as ALS. Opregion potentially mitigates these problems, but I've still 
seen some cases where the distinction matters.

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

  reply	other threads:[~2011-04-13 13:23 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-13  9:35 [PATCH 1/5] gma500: ioctl first pass Alan Cox
2011-04-13  9:35 ` [PATCH 2/5] gma500: prepare to do some actual memory management Alan Cox
2011-04-13  9:36 ` [PATCH 3/5] gma500: backlight warning Alan Cox
2011-04-13 13:17   ` Matthew Garrett
2011-04-13 13:20     ` Alan Cox
2011-04-13 13:23       ` Matthew Garrett [this message]
2011-04-13  9:37 ` [PATCH 4/5] gma500: Add a gtt allocator Alan Cox
2011-04-13 10:37   ` Thierry Reding
2011-04-13  9:37 ` [PATCH 5/5] gma500: Tidy up the allocations Alan Cox

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