Re: [PATCH 1/4] drm/atomic: Save flip flags in drm_plane_state

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Jan 23, 2017 at 07:48:54PM +0000, Cheng, Tony wrote:
> 
> 
> > -----Original Message-----
> > From: dri-devel [mailto:dri-devel-bounces@lists.freedesktop.org] On Behalf
> > Of Daniel Vetter
> > Sent: Monday, January 23, 2017 3:55 AM
> > To: Grodzovsky, Andrey <Andrey.Grodzovsky@amd.com>
> > Cc: Deucher, Alexander <Alexander.Deucher@amd.com>;
> > nouveau@lists.freedesktop.org; amd-gfx@lists.freedesktop.org; dri-
> > devel@lists.freedesktop.org; daniel.vetter@intel.com
> > Subject: Re: [PATCH 1/4] drm/atomic: Save flip flags in drm_plane_state
> > 
> > On Mon, Jan 16, 2017 at 10:44:55AM -0500, Andrey Grodzovsky wrote:
> > > Allows using atomic flip helpers for drivers using ASYNC flip.
> > > Remove ASYNC_FLIP restriction in helpers and caches the page flip
> > > flags in drm_plane_state to be used in the low level drivers.
> > >
> > > Signed-off-by: Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>
> > 
> > It's mostly guesswork, but I think we should have the flip flags in the crtc, not
> > in each plane. Similar to how we move the event from planes to crtc.
> > -Daniel
> 
> What does ASYNC flip mean?  HW flip as soon as possible and result in
> tearing on screen?  If so I could imaging some use case where you have
> some UI control/menu overlay on top, and some game running on a underlay
> plane, and the game want to be able to flip as soon as possible.  Or
> Daniel do you think ASYNC property will apply to all planes in CRTC?

Those kind of questions are exactly why I think we should wait with
exposing async through the atomic ioctl until someone needs it. And yes
async means "as fast as possible, with tearing".
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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