[PATCH xserver] modesetting: Fix page flipping under DRI 3.2.

[Mario Kleiner]

Ok, so it's probably a mesa bug in the egl dri3 backend caused by the
new DRI3.1 multibuffers support.

If on current mesa master, in egl_dri2.c:dri2_setup_extensions(), i
force dri2_dpy->multibuffers_available = false; to disable
multibuffers, then EGL based compositing under DRI3 works fine again.
Otherwise i get failure on all gpu's and drivers, as tested with
ati-ddx,nouveau-ddx,modesetting-ddx under glamor or exa.

This tested on current xserver master and Linux drm-next.

Bedtime here,
-mario


On Tue, Apr 3, 2018 at 7:17 PM, Mario Kleiner
<mario.kleiner.de at gmail.com> wrote:
> Will check it later when i'm at the machines. But does Ivybridge/Gen-7
> even have CCS? I can't test with something more modern Intel atm.
>
> -mario
>
>
> On Tue, Apr 3, 2018 at 5:57 PM, Daniel Stone <daniel at fooishbar.org> wrote:
>> On 3 April 2018 at 16:36, Mario Kleiner <mario.kleiner.de at gmail.com> wrote:
>>> Btw. another new problem, which i haven't had time to track down at
>>> all is that desktop composition under EGL seems to be totally broken.
>>> Tested on KUbuntu 16.0.4 LTS with xserver master + mesa master last
>>> thursday with whatever KDE Plasma 5 version ships with 16.04.
>>> Compositing with XRender accel or GLX + OpenGL 2/3 works fine. Could
>>> be modesetting, or glamor, or mesa.
>>>
>>> I get sometimes black screen, or sometimes massive corruption with
>>> pixel trash like if it displays random buffer contents from
>>> uninitialized buffers under modesetting-ddx + DRI3, on all kms
>>> drivers. Can anybody confirm this?
>>
>> It is seeming like the compression support in the Intel driver has
>> regressed. If you edit mesa/src/mesa/drivers/dri/i965/intel_screen.c
>> and remove I915_FORMAT_MOD_Y_TILED_CCS from the supported_modifiers[]
>> array, does that resolve the issue?
>>
>> Cheers,
>> Daniel