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Date: Sun, 13 Mar 2011 16:28:12 +0000
From: Matthew Garrett <mjg59@srcf.ucam.org>
To: Greg KH <greg@kroah.com>
Cc: Nikolai Kondrashov <spbnick@gmail.com>,
        Randy Dunlap <rdunlap@xenotime.net>, linux-kernel@vger.kernel.org,
        platform-driver-x86@vger.kernel.org
Subject: Re: [PATCH] Platform: add Samsung Laptop platform driver
Message-ID: <20110313162812.GA25369@srcf.ucam.org>
References: <4D793D05.3070908@gmail.com> <20110310211519.GA11862@kroah.com> <4D79CB47.2030405@gmail.com> <20110311170313.GA10202@kroah.com> <4D7A72E3.1050407@gmail.com> <20110311193433.GB14204@kroah.com> <4D7A8419.6080107@gmail.com> <20110311203032.GA14384@kroah.com> <4D7C9668.3000902@gmail.com> <20110313161752.GC10718@kroah.com>
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On Sun, Mar 13, 2011 at 09:17:53AM -0700, Greg KH wrote:
> On Sun, Mar 13, 2011 at 12:03:20PM +0200, Nikolai Kondrashov wrote:
> > Sometime ago I've found this hack on some forum, which I use currently
> > to set the brightness:
> > 
> > setpci -s 00:02.0 f4.b="$HEX_BYTE"
> > 
> > It allows finer control of the brightness, but it seems it operates directly
> > on the video card PCI register. I assume there is no sane way to use
> > this interface from the platform driver, right?
> 
> Yes, do not do this, it causes all sorts of problems in the end, not the
> least being the BIOS doesn't know what is going on at all as you are
> changing the brightness without it knowing it.

It's also modifying configuration that belongs to a device being managed 
by another driver, so it's the kind of thing we frown upon. Having said 
that, the Intel driver should gain native backlight support in .39.

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