[Mesa-dev] [PATCH 1/2] gbm: Enable DRI2 fence extension in the GBM DRI backend

[Philipp Zabel]

Hi Marek,

Am Mittwoch, den 25.05.2016, 20:52 +0200 schrieb Marek Olšák:
> On Wed, May 25, 2016 at 4:46 PM, Philipp Zabel <p.zabel at pengutronix.de> wrote:
> > Am Mittwoch, den 25.05.2016, 16:01 +0200 schrieb Marek Olšák:
> >> On Wed, May 25, 2016 at 3:44 PM, Philipp Zabel <p.zabel at pengutronix.de> wrote:
> >> > Am Dienstag, den 10.05.2016, 17:35 +0200 schrieb Philipp Zabel:
> >> >> To support the EGL_KHR_fence_sync extension on the DRM EGL platform,
> >> >> add the DRI2 fence extension to the dri_core_extensions match table.
> >> >>
> >> >> Signed-off-by: Philipp Zabel <p.zabel at pengutronix.de>
> >> >
> >> > Gentle ping. Is this about the right way to enable the
> >> > EGL_KHR_fence_sync extension on DRM EGL platforms?
> >>
> >> Unlikely. Where are the __DRI2fenceExtension callbacks implemented?
> >
> > The callbacks are implemented and added to the dri_screen_extensions[]
> > array in src/gallium/state_trackers/dri/dri2.c. The array is assigned to
> > the __DRIscreen member "extensions" in dri2_init_screen().
> >
> > dri_screen_create_dri2() in src/gbm/backends/dri/gbm_dri.c
> > then obtains the extensions array via dri->core->getExtensions() and
> > binds selected extensions to the gbm_dri_device according to the
> > placement information in the dri_core_extensions[] array.
> > This was already done for the flush and image extensions, so I have
> > similarly added a fence extension pointer to the gbm_dri_device and an
> > entry to dri_core_extensions to have it initialized from the dri2
> > extension array that already contained the fence extension.
> >
> > dri2_initialize_drm() in src/egl/drivers/dri2/platform_drm.c
> > then copies the extension pointers from the gbm_dri_device
> > dri2_dpy->gbm_dri into the dri2_egl_display dri2_dpy proper.
> > This also was already done for a few other extensions, among them image
> > and flush, and the dri2_egl_display already has a fence pointer that I
> > used to assign to the gbm_dri_device's new fence pointer.
> >
> > dri2_setup_screen() in src/egl/drivers/dri2/egl_dri2.c later checks
> > dri2_dpy->fence to enable the extension.
> 
> As you can see, I'm not very familiar with libgbm. Hopefully somebody
> else will take a look.

Ok, thanks. As you can see from my rambling reply versus Emil's succinct
summary, I am not either. Just followed the breadcrumbs and found you
two at the top of get_reviewer.pl output.

regards
Philipp