Re: [PATCH 7/9] drm/gem-fb-helper: Always do implicit sync

From: Daniel Vetter <daniel@ffwll.ch>
To: Eric Anholt <eric@anholt.net>
Cc: David Airlie <airlied@linux.ie>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	Gustavo Padovan <gustavo.padovan@collabora.co.uk>,
	DRI Development <dri-devel@lists.freedesktop.org>,
	Daniel Vetter <daniel.vetter@intel.com>
Subject: Re: [PATCH 7/9] drm/gem-fb-helper: Always do implicit sync
Date: Tue, 24 Apr 2018 14:04:10 +0200	[thread overview]
Message-ID: <20180424120410.GV31310@phenom.ffwll.local> (raw)
In-Reply-To: <87bmedil4j.fsf@anholt.net>

On Fri, Apr 20, 2018 at 03:11:24PM -0700, Eric Anholt wrote:
> Daniel Vetter <daniel.vetter@ffwll.ch> writes:
> 
> > I've done a lot of history digging. The first signs of this
> > optimization was introduced in i915:
> 
> I can't come up with any reason this would matter.  I almost came up
> with "You're doing tearing X11 front buffer rendering, and you do a
> modeset using the same fb, and so you block that modeset behind your
> rendering."  Except that:
> 
> 1) who cares
> 2) this helper is only for dma-bufs, not normal X11 rendering
> 3) your X11 driver should be doing pageflipping to be tear-free anyway,
>    let's just fix that[1].
> 
> Reviewed-by: Eric Anholt <eric@anholt.net>
> 
> [1] This is not actually me volunteering myself or anyone else to go fix
> that.

Ok, merged everything except the final three patches. I'll poke Rob for a
proper ack first before doing that. There's not much point in trying to
unify behaviour if there's still a driver doing things differently :-)

Thanks very much for your review.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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