[PATCH 0/3] Tegra Host1x dma_fence/sync_file support

[Daniel Vetter]

On Thu, Mar 09, 2017 at 09:09:52PM +0200, Mikko Perttunen wrote:
> On 03/09/2017 08:58 PM, Daniel Vetter wrote:
> > On Thu, Mar 9, 2017 at 6:57 PM, Mikko Perttunen <mperttunen at nvidia.com> wrote:
> > > Hi everyone,
> > > 
> > > this series adds support for using sync fences as prefences and
> > > postfences for host1x job submissions. The patches are available
> > > as a git repository at
> > > 
> > >   https://github.com/cyndis/linux/tree/host1x-fence-1
> > > 
> > > and testing code is available at
> > > 
> > >   https://github.com/cyndis/host1x_test
> > > 
> > > though you may want to edit the main function to disable the
> > > timeout tests for now as they cause a deadlock (not caused
> > > by this series; fix upcoming).
> > > 
> > > Verified on a Jetson TX1; should go on top of the earlier
> > > VIC series.
> > > 
> > > Some additional points:
> > > * I noticed that the waitchk_mask field in the submit UAPI is completely
> > >   useless, and has never had any effect in the upstream kernel.
> > >   It has also not existed in the downstream kernel for many years.
> > >   We could replace it with the flags field if that is deemed
> > >   acceptable, though of course it is possible there exists some
> > >   application that fills it with some non-zero value.
> > 
> > If open source userspace (nouveau_dri.so) never used it, then you can
> > freely change it. Backwards compat guarantee in drm is only for open
> > source userspace (and by implication ofc anything that uses the ioctl
> > the same way). See:
> > 
> > https://dri.freedesktop.org/docs/drm/gpu/drm-uapi.html#open-source-userspace-requirements
> 
> nouveau doesn't have any host1x related code - so no, there is no
> pre-existing open-source userspace that uses this :)
> 
> > 
> > On that topic, do we have the nouveau patches to enable the
> > egl_android extension for this already published?
> 
> I assume you are referring to EGL_ANDROID_native_fence_sync; I don't know
> what nouveau's status is regarding that. With this series, the host1x driver
> does not yet allow other drivers access to the raw syncpoint values behind
> host1x fences but that can be fixed pretty easily if/when nouveau wants to
> support native syncpoint waits on Tegra.
> Host1x jobs do use native waits already with this series, though.

Well you're adding new uapi to the tegra drm driver, and
EGL_ANDROID_native_fence_sync for nouveau seems like the real use-case for
this. Which means we need that, before we can merge these patches.

At least I assume that this was done for the nv blob tegra gl driver? Of
course if there's some other reasonable use-case, we can use that as open
source demonstration thing too.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch