drm/i915: framebuffer compression for pre-GM45

This patch adds framebuffer compression (good for about ~0.5W power
savings in the best case) support for pre-GM45 chips.  GM45+ have a new,
more flexible FBC scheme that will be added in a separate patch.

FBC can't always be enabled: the compressed buffer must be physically
contiguous and reside in stolen space.  So if you have a large display
and a small amount of stolen memory, you may not be able to take
advantage of FBC.  In some cases, a BIOS setting controls how much
stolen space is available.  Increasing this to 8 or 16M can help.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index b9e47f1..7478196 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -28,6 +28,7 @@
 #include <linux/i2c.h>
 #include <linux/i2c-id.h>
 #include <linux/i2c-algo-bit.h>
+#include "i915_drv.h"
 #include "drm_crtc.h"
 
 #include "drm_crtc_helper.h"
@@ -110,8 +111,8 @@
 
 struct intel_crtc {
 	struct drm_crtc base;
-	int pipe;
-	int plane;
+	enum pipe pipe;
+	enum plane plane;
 	struct drm_gem_object *cursor_bo;
 	uint32_t cursor_addr;
 	u8 lut_r[256], lut_g[256], lut_b[256];