drm/i915: Compute display FIFO split dynamically for CHV

Consider which planes are active and compute the FIFO split based on the
relative data rates. Since we only consider the pipe src width rather
than the plane width when computing watermarks it seems best to do the
same when computing the FIFO split as well. This means the only thing we
actually have to consider for the FIFO splut is the bpp, and we can
ignore the rest.

I've just stuffed the logic into the watermark code for now. Eventually
it'll need to move into the atomic update for the crtc.

There's also one extra complication I've not yet considered; Some of the
DSPARB registers contain bits related to multiple pipes. The registers
are double buffered but apparently they update on the vblank of any
active pipe. So doing the FIFO reconfiguration properly when multiple
pipes are active is not going to be fun. But let's ignore that mess for
now.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Clint Taylor <Clinton.A.Taylor@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index b6c8037..50e6279 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -4415,9 +4415,32 @@
 #define   DSPARB_BSTART_SHIFT	0
 #define   DSPARB_BEND_SHIFT	9 /* on 855 */
 #define   DSPARB_AEND_SHIFT	0
-
+#define   DSPARB_SPRITEA_SHIFT_VLV	0
+#define   DSPARB_SPRITEA_MASK_VLV	(0xff << 0)
+#define   DSPARB_SPRITEB_SHIFT_VLV	8
+#define   DSPARB_SPRITEB_MASK_VLV	(0xff << 8)
+#define   DSPARB_SPRITEC_SHIFT_VLV	16
+#define   DSPARB_SPRITEC_MASK_VLV	(0xff << 16)
+#define   DSPARB_SPRITED_SHIFT_VLV	24
+#define   DSPARB_SPRITED_MASK_VLV	(0xff << 24)
 #define DSPARB2			(VLV_DISPLAY_BASE + 0x70060) /* vlv/chv */
+#define   DSPARB_SPRITEA_HI_SHIFT_VLV	0
+#define   DSPARB_SPRITEA_HI_MASK_VLV	(0x1 << 0)
+#define   DSPARB_SPRITEB_HI_SHIFT_VLV	4
+#define   DSPARB_SPRITEB_HI_MASK_VLV	(0x1 << 4)
+#define   DSPARB_SPRITEC_HI_SHIFT_VLV	8
+#define   DSPARB_SPRITEC_HI_MASK_VLV	(0x1 << 8)
+#define   DSPARB_SPRITED_HI_SHIFT_VLV	12
+#define   DSPARB_SPRITED_HI_MASK_VLV	(0x1 << 12)
+#define   DSPARB_SPRITEE_HI_SHIFT_VLV	16
+#define   DSPARB_SPRITEE_HI_MASK_VLV	(0x1 << 16)
+#define   DSPARB_SPRITEF_HI_SHIFT_VLV	20
+#define   DSPARB_SPRITEF_HI_MASK_VLV	(0x1 << 20)
 #define DSPARB3			(VLV_DISPLAY_BASE + 0x7006c) /* chv */
+#define   DSPARB_SPRITEE_SHIFT_VLV	0
+#define   DSPARB_SPRITEE_MASK_VLV	(0xff << 0)
+#define   DSPARB_SPRITEF_SHIFT_VLV	8
+#define   DSPARB_SPRITEF_MASK_VLV	(0xff << 8)
 
 /* pnv/gen4/g4x/vlv/chv */
 #define DSPFW1			(dev_priv->info.display_mmio_offset + 0x70034)