drm/i915: kill mappable/fenceable disdinction

a00b10c360b35d6431a "Only enforce fence limits inside the GTT" also
added a fenceable/mappable disdinction when binding/pinning buffers.
This only complicates the code with no pratical gain:

- In execbuffer this matters on for g33/pineview, as this is the only
  chip that needs fences and has an unmappable gtt area. But fences
  are only possible in the mappable part of the gtt, so need_fence
  implies need_mappable. And need_mappable is only set independantly
  with relocations which implies (for sane userspace) that the buffer
  is untiled.

- The overlay code is only really used on i8xx, which doesn't have
  unmappable gtt. And it doesn't support tiled buffers, currently.

- For all other buffers it's a bug to pass in a tiled bo.

In short, this disdinction doesn't have any practical gain.

I've also reverted mapping the overlay and context pages as possibly
unmappable. It's not worth being overtly clever here, all the big
gains from unmappable are for execbuf bos.

Also add a comment for a clever optimization that confused me
while reading the original patch by Chris Wilson.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 7 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 48d0aefec1f..62123426545 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -752,8 +752,6 @@ struct drm_i915_gem_object {
 	 * Advice: are the backing pages purgeable?
 	 */
 	unsigned int madv : 2;
-	unsigned int fenceable : 1;
-	unsigned int mappable : 1;
 
 	/**
 	 * Current tiling mode for the object.
@@ -773,6 +771,12 @@ struct drm_i915_gem_object {
 #define DRM_I915_GEM_OBJECT_MAX_PIN_COUNT 0xf
 
 	/**
+	 * Is the object at the current location in the gtt mappable and
+	 * fenceable? Used to avoid costly recalculations.
+	 */
+	unsigned int map_and_fenceable : 1;
+
+	/**
 	 * Whether the current gtt mapping needs to be mappable (and isn't just
 	 * mappable by accident). Track pin and fault separate for a more
 	 * accurate mappable working set.
@@ -1013,7 +1017,7 @@ struct drm_gem_object * i915_gem_alloc_object(struct drm_device *dev,
 					      size_t size);
 void i915_gem_free_object(struct drm_gem_object *obj);
 int i915_gem_object_pin(struct drm_gem_object *obj, uint32_t alignment,
-			bool mappable, bool need_fence);
+			bool map_and_fenceable);
 void i915_gem_object_unpin(struct drm_gem_object *obj);
 int i915_gem_object_unbind(struct drm_gem_object *obj);
 void i915_gem_release_mmap(struct drm_gem_object *obj);