[Intel-gfx] [PATCH] drm/i915: disable set/get_tiling ioctl on gen12+

[Daniel Vetter]

On Tue, Aug 20, 2019 at 8:55 PM Chris Wilson <chris at chris-wilson.co.uk> wrote:
>
> Quoting Daniel Vetter (2019-08-20 18:06:31)
> > The cpu (de)tiler hw is gone, this stopped being useful. Plus it never
> > supported any of the fancy new tiling formats, which means userspace
> > also stopped using the magic side-channel this provides.
> >
> > This would totally break a lot of the igts, but they're already broken
> > for the same reasons as userspace on gen12 would be.
> >
> > Cc: Kenneth Graunke <kenneth at whitecape.org>
> > Cc: Jason Ekstrand <jason at jlekstrand.net>
> > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Lucas De Marchi <lucas.demarchi at intel.com>
> > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> > ---
> >  drivers/gpu/drm/i915/gem/i915_gem_tiling.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_tiling.c b/drivers/gpu/drm/i915/gem/i915_gem_tiling.c
> > index ca0c2f451742..2ee96f27a294 100644
> > --- a/drivers/gpu/drm/i915/gem/i915_gem_tiling.c
> > +++ b/drivers/gpu/drm/i915/gem/i915_gem_tiling.c
> > @@ -313,10 +313,15 @@ int
> >  i915_gem_set_tiling_ioctl(struct drm_device *dev, void *data,
> >                           struct drm_file *file)
> >  {
> > +       struct drm_i915_private *dev_priv = to_i915(dev);
> >         struct drm_i915_gem_set_tiling *args = data;
> >         struct drm_i915_gem_object *obj;
> >         int err;
> >
> > +       /* there is no cpu (de)tiling in the hw anymore on gen12+ */
> > +       if (INTEL_GEN(dev_priv) >= 12)
>
> This should be if (!NUM_FENCES(dev_priv)) if anything. You wouldn't even
> need the comment talking about random features, and instead focus on why
> not supporting the back channel is worth the maintenance cost of
> divergence.

Yeah that's much better.

> > +               return -EOPNOTSUPP;
> > +
> >         obj = i915_gem_object_lookup(file, args->handle);
> >         if (!obj)
> >                 return -ENOENT;
> > @@ -402,6 +407,9 @@ i915_gem_get_tiling_ioctl(struct drm_device *dev, void *data,
> >         struct drm_i915_gem_object *obj;
> >         int err = -ENOENT;
> >
> > +       if (INTEL_GEN(dev_priv) >= 12)
> > +               return -EOPNOTSUPP;
>
> Not required.

I figured since we have a lot of old libdrm that loved to do
get_tiling this would help in catching them. That's why I put it in.
Plus just some ocd, if the set is gone, kill the get one too. Otoh we
might stir something up.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch