[Intel-gfx] [PATCH] drm/i915: Avoid snooping with userptr where not supported

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

   commit e5756c10d841ddb448293c849392f3d6b809561f
   Author: Imre Deak <imre.deak at intel.com>
   Date:   Fri Aug 14 18:43:30 2015 +0300

       drm/i915/bxt: don't allow cached GEM mappings on A stepping

Added an exception of disallowing snooping for Broxton A
stepping hardware but userptr was still enabling it regardless.

Move the check to HAS_SNOOP now that it is used from multiple
call sites and use it.

Idea is that userspace which relies on userptr snooping, for
example for fine grained buffered SVM, can query the caching
mode on a created userptr object to determine whether coherency
is supported or not.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h         | 1 +
 drivers/gpu/drm/i915/i915_gem.c         | 2 +-
 drivers/gpu/drm/i915/i915_gem_userptr.c | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 671295523317..73f0db17b990 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2629,6 +2629,7 @@ struct drm_i915_cmd_table {
 #define HAS_LLC(dev)		(INTEL_INFO(dev)->has_llc)
 #define HAS_WT(dev)		((IS_HASWELL(dev) || IS_BROADWELL(dev)) && \
 				 __I915__(dev)->ellc_size)
+#define HAS_SNOOP(dev)		(!IS_BXT_REVID(dev, 0, BXT_REVID_A1))
 #define I915_NEED_GFX_HWS(dev)	(INTEL_INFO(dev)->need_gfx_hws)
 
 #define HAS_HW_CONTEXTS(dev)	(INTEL_INFO(dev)->gen >= 6)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 3d31d3ac589e..1c6e8fb9d392 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3949,7 +3949,7 @@ int i915_gem_set_caching_ioctl(struct drm_device *dev, void *data,
 		 * cacheline, whereas normally such cachelines would get
 		 * invalidated.
 		 */
-		if (IS_BXT_REVID(dev, 0, BXT_REVID_A1))
+		if (!HAS_SNOOP(dev))
 			return -ENODEV;
 
 		level = I915_CACHE_LLC;
diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index 4b09c840d493..48aaff019b42 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -782,7 +782,7 @@ i915_gem_userptr_ioctl(struct drm_device *dev, void *data, struct drm_file *file
 
 	drm_gem_private_object_init(dev, &obj->base, args->user_size);
 	i915_gem_object_init(obj, &i915_gem_userptr_ops);
-	obj->cache_level = I915_CACHE_LLC;
+	obj->cache_level = HAS_SNOOP(dev) ? I915_CACHE_LLC : I915_CACHE_NONE;
 	obj->base.write_domain = I915_GEM_DOMAIN_CPU;
 	obj->base.read_domains = I915_GEM_DOMAIN_CPU;
 
-- 
1.9.1