Re: [PATCH 3/3] drm/i915: Use intel_plane_obj_offset from more places

From: Daniel Vetter <daniel@ffwll.ch>
To: Chris Wilson <chris@chris-wilson.co.uk>,
	Daniel Vetter <daniel@ffwll.ch>,
	Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
	Intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 3/3] drm/i915: Use intel_plane_obj_offset from more places
Date: Thu, 28 May 2015 16:09:37 +0200	[thread overview]
Message-ID: <20150528140937.GH8341@phenom.ffwll.local> (raw)
In-Reply-To: <20150528123654.GC19710@nuc-i3427.alporthouse.com>

On Thu, May 28, 2015 at 01:36:54PM +0100, Chris Wilson wrote:
> On Thu, May 28, 2015 at 02:24:40PM +0200, Daniel Vetter wrote:
> > On Thu, May 28, 2015 at 09:58:30AM +0100, Tvrtko Ursulin wrote:
> > > 
> > > On 05/27/2015 10:15 PM, Chris Wilson wrote:
> > > >On Wed, May 27, 2015 at 10:52:34AM +0100, Tvrtko Ursulin wrote:
> > > >>From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> > > >>
> > > >>These are the display call sites so should use the proper helper.
> > > >>
> > > >>Also requires intel_plane_obj_offset to assume normal view when
> > > >>plane pointer is not available.
> > > >
> > > >Eugh. If only the plane stored the offset, bonus marks for storing the
> > > >vma cookie, then we would not have to keep recomputing the view and
> > > >searching every single time...
> > > 
> > > Well, the patch even decreases the number of searches! :)
> > > 
> > > And we don't recompute when querying the offset - it just figures out what
> > > type of vma it should look for. So I think it doesn't prevent any future
> > > caching improvements. It actually makes it easier since it consolidates the
> > > query.
> > > 
> > > I'll need this, or something like it, for some future work. So at the very
> > > moment I am not too bothered if this goes in or not.
> > 
> > Yeah unfortunately we can't eliminate the view searches completely since
> > the view depends upon fb + plane_state. So not perfectly aligned with our
> > hw ... Otherwise I'd agree, caching the view in the fb would be neat.
> 
> Not in the fb, in the plane_state. We acquire the vma for the plane
> during prepare and then we should be using that vma reference for the
> lifetime of that atomic plane state.

Hm right that should work. And the pin will make sure it won't go poof
prematurely.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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