Re: [RFC][PATCH 2/3] drm: vgem: Enable SYNCOBJ and SYNCOBJ_TIMELINE on vgem driver

[Christian König]

Am 12.07.22 um 18:50 schrieb John Stultz:
> On Tue, Jul 12, 2022 at 12:46 AM Christian König
> <christian.koenig@xxxxxxx> wrote:
> > Am 12.07.22 um 06:22 schrieb John Stultz:
> > > Allows for basic SYNCOBJ api testing, in environments
> > > like VMs where there may not be a supported drm driver.
> > >
> > > Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> > > Cc: Maxime Ripard <mripard@xxxxxxxxxx>
> > > Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> > > Cc: Jason Ekstrand <jason@xxxxxxxxxxxxxx>
> > > Cc: Christian König <christian.koenig@xxxxxxx>
> > > Cc: Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxx>
> > > Cc: Chunming Zhou <david1.zhou@xxxxxxx>
> > > Cc: David Airlie <airlied@xxxxxxxx>
> > > Cc: Daniel Vetter <daniel@xxxxxxxx>
> > > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > > Signed-off-by: John Stultz <jstultz@xxxxxxxxxx>
> > > ---
> > >    drivers/gpu/drm/vgem/vgem_drv.c | 3 ++-
> > >    1 file changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> > > index c5e3e5457737..e5427d7399da 100644
> > > --- a/drivers/gpu/drm/vgem/vgem_drv.c
> > > +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> > > @@ -109,7 +109,8 @@ static struct drm_gem_object *vgem_gem_create_object(struct drm_device *dev, siz
> > >    }
> > >
> > >    static const struct drm_driver vgem_driver = {
> > > -     .driver_features                = DRIVER_GEM | DRIVER_RENDER,
> > > +     .driver_features                = DRIVER_GEM | DRIVER_RENDER |
> > > +                                       DRIVER_SYNCOBJ | DRIVER_SYNCOBJ_TIMELINE,
> > Well that's rather surprising. I'm not an export on VGEM, but AFAIK you
> > need to adjust the CS interface to support that stuff as well.
> Apologies, could you clarify a bit more what you mean here?  This was
> just helpful to enable the generic userland ioctls for the example
> test tool in this series.
>
> Are you proposing to add interfaces so the vgem driver can
> attach/signal syncobjs similar to the
> DRM_IOCTL_VGEM_FENCE_ATTACH/DRM_IOCTL_VGEM_FENCE_SIGNAL calls?

Yes, exactly that. I don't see how it would be useful otherwise.

Christian.

> thanks
> -john