drm/i915: disable set/get_tiling ioctl on gen12+

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.

v2: Look at ggtt->num_fences instead, that also avoids the need for a
comment (Chris). This also means that gen12 support really needs to
make sure num_fences is set to 0. There is a patch for that, but it
checks for HAS_MAPPABLE_APERTURE, which I'm not sure is the right
thing really. Adding relevant people.

Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Stuart Summers <stuart.summers@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Kenneth Graunke <kenneth@whitecape.org>
Cc: Jason Ekstrand <jason@jlekstrand.net>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NJosé Roberto de Souza <jose.souza@intel.com>
Reviewed-by: NJosé Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190820195451.15671-1-daniel.vetter@ffwll.ch

drivers/gpu/drm/i915/gem/i915_gem_tiling.c

@@ -313,10 +313,14 @@ 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;
 
+	if (!dev_priv->ggtt.num_fences)
+		return -EOPNOTSUPP;
+
 	obj = i915_gem_object_lookup(file, args->handle);
 	if (!obj)
 		return -ENOENT;
@@ -402,6 +406,9 @@ i915_gem_get_tiling_ioctl(struct drm_device *dev, void *data,
 	struct drm_i915_gem_object *obj;
 	int err = -ENOENT;
 
+	if (!dev_priv->ggtt.num_fences)
+		return -EOPNOTSUPP;
+
 	rcu_read_lock();
 	obj = i915_gem_object_lookup_rcu(file, args->handle);
 	if (obj) {