@@ -3342,6 +3342,14 @@ int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
if (obj->cache_level == cache_level)
return 0;
+ if (INTEL_INFO(obj->base.dev)->gen < 6 &&
+ obj->tiling_mode != I915_TILING_NONE &&
+ cache_level != I915_CACHE_NONE) {
+ DRM_DEBUG("can not enable snooping on a tiled surface, "
+ "it must be linear for pre-SandyBridge chipsets\n");
+ return -EINVAL;
+ }
+
if (obj->gtt_space) {
ret = i915_gem_object_flush_gpu(obj);
if (ret)
@@ -331,6 +331,14 @@ i915_gem_set_tiling(struct drm_device *dev, void *data,
}
mutex_lock(&dev->struct_mutex);
+ if (INTEL_INFO(dev)->gen < 6 &&
+ args->tiling_mode != I915_TILING_NONE &&
+ obj->cache_level != I915_CACHE_NONE) {
+ DRM_DEBUG("can't not set a tiling mode on snooped memory,"
+ "it must be linear for pre-SandyBridge chipsets\n");
+ ret = -EINVAL;
+ goto err;
+ }
if (args->tiling_mode != obj->tiling_mode ||
args->stride != obj->stride) {
/* We need to rebind the object if its current allocation
@@ -363,6 +371,7 @@ i915_gem_set_tiling(struct drm_device *dev, void *data,
}
}
/* we have to maintain this existing ABI... */
+err:
args->stride = obj->stride;
args->tiling_mode = obj->tiling_mode;
drm_gem_object_unreference(&obj->base);
Older chipsets do not support snooping (i.e. cache sharing between the CPU and GPU) on tiled surfaces. So prevent userspace from being silly should we one day expose the ability to change cache levels from userspace. It does enforce a strict ordering for mode changing though. So in order to change a buffer to snooped, the driver has to clear any tiling first and then change the cache level. This is consistent with how we flush and update the PTEs and seems a reasonable imposition on the driver. Deferring the check until use, whilst providing flexibilty here, implies forcing extra unbinds and a more complicated error message from, for example, execbuffer. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> --- drivers/gpu/drm/i915/i915_gem.c | 8 ++++++++ drivers/gpu/drm/i915/i915_gem_tiling.c | 9 +++++++++ 2 files changed, 17 insertions(+), 0 deletions(-)