linux-kernel - Re: drm/radeon/kms: fix up LVDS handling on macs (v2)

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Date:	Thu, 14 Jan 2010 11:09:41 +0100
From:	Michel Dänzer <michel@...nzer.net>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:	Alex Deucher <alexdeucher@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Dave Airlie <airlied@...hat.com>
Subject: Re: drm/radeon/kms: fix up LVDS handling on macs (v2)

On Thu, 2010-01-14 at 13:45 +1100, Benjamin Herrenschmidt wrote: 
> On Thu, 2010-01-14 at 00:59 +0000, Linux Kernel Mailing List wrote:
> > Gitweb:     http://git.kernel.org/linus/3890ddf56dbc0f804953198e65a7e406ed654576
> > Commit:     3890ddf56dbc0f804953198e65a7e406ed654576
> > Parent:     804c7559e9376c3ba78ae15a30337b1e24f8ae80
> > Author:     Alex Deucher <alexdeucher@...il.com>
> > AuthorDate: Tue Jan 12 11:16:57 2010 -0500
> > Committer:  Dave Airlie <airlied@...hat.com>
> > CommitDate: Wed Jan 13 13:25:08 2010 +1000
> > 
> >     drm/radeon/kms: fix up LVDS handling on macs (v2)
> >     
> >     Based on radeonfb code and recent ddx fix.
> >     
> >     v2: minor formatting fix from Michel Dänzer
> >     
> >     Signed-off-by: Alex Deucher <alexdeucher@...il.com>
> >     Reviewed-by: Michel Dänzer <michel@...nzer.net>
> >     Tested-by: Michel Dänzer <michel@...nzer.net>
> >     Signed-off-by: Dave Airlie <airlied@...hat.com>
> 
> I have to dbl check that ... but I think the "Real" issue is that some
> panel have inverted polarity on the PWM signal. Thus if BLON is turned
> off the panels goes full backlight instead among other things :-)
> 
> However, not all macs are the same. If you look at the radeonfb code,
> we do things differently depending on the mac model...

I have looked at radeonfb for a patch I posted a while ago to expose a
backlight class device with KMS, and I can only see what you describe
above affecting the LVDS_GEN_CNTL backlight level, not BLON or
BL_MOD_EN. Am I missing something?

Without my patch, KMS doesn't change the backlight level at all, so
assuming the firmware manages to enable the backlight, it should stay
like that.


-- 
Earthling Michel Dänzer           |                http://www.vmware.com
Libre software enthusiast         |          Debian, X and DRI developer
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