Re: [RFC PATCH 3/5] drm/i915: register LVDS connector even if we can't get a panel mode

From: Daniel Vetter <daniel@ffwll.ch>
To: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: dri-devel@lists.freedesktop.org, David Airlie <airlied@linux.ie>,
	linux-kernel@vger.kernel.org, Andreas Heider <andreas@meetr.de>
Subject: Re: [RFC PATCH 3/5] drm/i915: register LVDS connector even if we can't get a panel mode
Date: Sun, 5 Aug 2012 23:40:16 +0200	[thread overview]
Message-ID: <20120805214016.GH12232@phenom.ffwll.local> (raw)
In-Reply-To: <20120805211838.GA27188@srcf.ucam.org>

On Sun, Aug 05, 2012 at 10:18:38PM +0100, Matthew Garrett wrote:
> On Sun, Aug 05, 2012 at 11:14:12PM +0200, Daniel Vetter wrote:
> 
> > I like this approach more - the only other solution I see is to ask the
> > currently active driver (i.e. radeon) at bootime for the right mode. Which
> > sounds much more hellish and fragile ...
> 
> The "correct" approach is clearly to just have the drm core change the 
> i2c mux before requesting edid, but that's made difficult because of the 
> absence of ordering guarantees in initialisation. I don't like quirking 
> this, since we're then back to the situation of potentially having to 
> add every new piece of related hardware to the quirk list.

The "correct" approach of switching the mux before we fetch the edid is
actualy the one I fear will result in fragile code: Only run on few
machines, and as you say with tons of funky interactions with the init
sequence ordering. And I guess people will bitch&moan about the flickering
this will cause ;-)

As long as it's only apple shipping multi-gpu machines with
broken/non-existing vbt, I'll happily stomach the quirk list entries.
They're bad, but imo the lesser evil.
-Daniel
-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48