diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 72374e952e4b..638ae277ff03 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -1484,17 +1484,37 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data, if ((write_domain | read_domains) & I915_GEM_GPU_DOMAINS) return -EINVAL; - /* Having something in the write domain implies it's in the read + /* + * Having something in the write domain implies it's in the read * domain, and only that read domain. Enforce that in the request. */ - if (write_domain != 0 && read_domains != write_domain) + if (write_domain && read_domains != write_domain) return -EINVAL; + if (!read_domains) + return 0; + obj = i915_gem_object_lookup(file, args->handle); if (!obj) return -ENOENT; - /* Try to flush the object off the GPU without holding the lock. + /* + * Already in the desired write domain? Nothing for us to do! + * + * We apply a little bit of cunning here to catch a broader set of + * no-ops. If obj->write_domain is set, we must be in the same + * obj->read_domains, and only that domain. Therefore, if that + * obj->write_domain matches the request read_domains, we are + * already in the same read/write domain and can skip the operation, + * without having to further check the requested write_domain. + */ + if (READ_ONCE(obj->write_domain) == read_domains) { + err = 0; + goto out; + } + + /* + * Try to flush the object off the GPU without holding the lock. * We will repeat the flush holding the lock in the normal manner * to catch cases where we are gazumped. */