[PATCH 1/3] RFC: drm: Restrict vblank ioctl to master

[Daniel Vetter]

On Mon, Jul 25, 2016 at 1:15 PM, Rainer Hochecker <fernetmenta at kodi.tv> wrote:
> Am 25.07.2016 08:38 schrieb "Michel Dänzer" <michel at daenzer.net>:
>>
>> On 13.07.2016 18:49, Rainer Hochecker wrote:
>> > We have been using this for years now and did not observe issues you
>> > mentioned. I would be surprised if a child window refreshes in a
>> > different rate than the main window
>>
>> The Xorg driver decides which CRTC to synchronize with based on the
>> window geometry. For a window with no visible geometry, it may choose a
>> different CRTC than for the visible output window. In the case of DRI3,
>> the Xorg Present extension code may even fall back to the fake CRTC in
>> that case, which only generates a fake vblank event once every second.
>>
>>
>> --
>> Earthling Michel Dänzer               |               http://www.amd.com
>> Libre software enthusiast             |             Mesa and X developer
>>
>
> That means that we won't have a solution for X11 with EGL for Intel systems
> anymore.

I didn't know about this, but a proper EGL extension, implemented on
X11 exists already:

https://codereview.chromium.org/2867513002/

It's not in the khronos registry, but mesa implements it, and
semantics match oml_sync (and wayland present), so we already have the
proper extension to implement this without digging around in device
files and making a guess about which pipe you might be running on.

Cheers, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch