I915_GEM_DOMAIN_WC
if (obj->write_domain == I915_GEM_DOMAIN_WC)
flush_write_domain(obj, ~I915_GEM_DOMAIN_WC);
if ((obj->read_domains & I915_GEM_DOMAIN_WC) == 0)
GEM_BUG_ON((obj->write_domain & ~I915_GEM_DOMAIN_WC) != 0);
obj->read_domains |= I915_GEM_DOMAIN_WC;
obj->read_domains = I915_GEM_DOMAIN_WC;
obj->write_domain = I915_GEM_DOMAIN_WC;
if (read_domains & I915_GEM_DOMAIN_WC)
case I915_GEM_DOMAIN_WC:
obj->write_domain = I915_GEM_DOMAIN_WC;
obj->read_domains = I915_GEM_DOMAIN_WC;