From mboxrd@z Thu Jan  1 00:00:00 1970
From: Matt Roper <matthew.d.roper@intel.com>
Subject: Re: [PATCH] drm/i915: Intel-specific primary plane
 handling (v2)
Date: Fri, 11 Apr 2014 10:41:56 -0700
Message-ID: <20140411174155.GH1063@intel.com>
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To: Daniel Vetter <daniel@ffwll.ch>
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On Fri, Apr 11, 2014 at 11:34:36AM +0200, Daniel Vetter wrote:
> On Thu, Apr 10, 2014 at 05:24:36PM -0700, Matt Roper wrote:
...
> 
> Hm, I've thought we could do a simple
> 
> 	if (intel_crtc->primary_enabled)
> 		call_primary_plane_helper
> 	else
> 		enable_the_hw_plane
> 
> But we need to do all the arg checking for the !primary_enabled case :(
> Anyway more code sharing make me happier.
> 
> Cheers, Daniel

I think the problem here is that the helper has a bunch of tests
targetted at the lowest common denominator hardware.  Some of the things
it rejects are things that our hardware may begin to allow at some point
in the future (e.g., primary plane scaling, partial CRTC coverage of
primary plane, etc.).  We can probably call into the helper today and
get the behavior we want, but I'd expect that some of those restrictions
will need to be relaxed in the future and then we'll have to switch the
code back at that point.  Given that we still need to do all this
checking in the 'if (!enabled)' case, I don't think it's worth trying to
call through the helper for the 'if (enabled)' case (especially since
the actual "work" here after we're done testing is just a couple lines
of code)?


Matt


-- 
Matt Roper
Graphics Software Engineer
IoTG Platform Enabling & Development
Intel Corporation
(916) 356-2795