[PATCH v2 3/3] drm/i915/uapi: reject set_domain for discrete

[Matthew Auld]

The CPU domain should be static for discrete, and on DG1 we don't need
any flushing since everything is already coherent, so really all this
does is an object wait, for which we have an ioctl. Longer term the
desired caching should be an immutable creation time property for the
BO, which can be set with something like gem_create_ext.

One other user is iris + userptr, which uses the set_domain to probe all
the pages to check if the GUP succeeds, however keeping the set_domain
around just for that seems rather scuffed. We could equally just submit
a dummy batch, which should hopefully be good enough, otherwise adding a
new creation time flag for userptr might be an option. Although longer
term we will also have vm_bind, which should also be a nice fit for
this, so adding a whole new flag is likely overkill.

Suggested-by: Daniel Vetter <daniel at ffwll.ch>
Signed-off-by: Matthew Auld <matthew.auld at intel.com>
Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Jordan Justen <jordan.l.justen at intel.com>
Cc: Kenneth Graunke <kenneth at whitecape.org>
Cc: Jason Ekstrand <jason at jlekstrand.net>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Ramalingam C <ramalingam.c at intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_domain.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_domain.c b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
index 43004bef55cb..b684a62bf3b0 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_domain.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
@@ -490,6 +490,9 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
 	u32 write_domain = args->write_domain;
 	int err;
 
+	if (IS_DGFX(to_i915(dev)))
+		return -ENODEV;
+
 	/* Only handle setting domains to types used by the CPU. */
 	if ((write_domain | read_domains) & I915_GEM_GPU_DOMAINS)
 		return -EINVAL;
-- 
2.26.3