drm/i915: Allow tiling of objects with bit 17 swizzling by the CPU.

Save the bit 17 state of the pages when freeing the page list, and
reswizzle them if necessary when rebinding the pages (in case they were
swapped out).  Since we have userland with expectations that the swizzle
enums let it pread and pwrite contents accurately, we can't expose a new
swizzle enum for bit 17 (which it would have to GTT map to handle), so we
handle it down in pread and pwrite by swizzling the copy when bit 17 of the
page address is set.

Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/include/drm/i915_drm.h b/include/drm/i915_drm.h
index 67e3353..95962fa 100644
--- a/include/drm/i915_drm.h
+++ b/include/drm/i915_drm.h
@@ -594,6 +594,9 @@
 #define I915_BIT_6_SWIZZLE_9_10_11	4
 /* Not seen by userland */
 #define I915_BIT_6_SWIZZLE_UNKNOWN	5
+/* Seen by userland. */
+#define I915_BIT_6_SWIZZLE_9_17		6
+#define I915_BIT_6_SWIZZLE_9_10_17	7
 
 struct drm_i915_gem_set_tiling {
 	/** Handle of the buffer to have its tiling state updated */