drm/i915/gen9: Store plane minimum blocks in CRTC wm state (v2)

This will eventually allow us to re-use old values without
re-calculating them for unchanged planes (which also helps us avoid
re-grabbing extra plane states).

v2:
 -  Drop unnecessary memset's; they were meant for a later patch (which
    got reworked anyway to not need them, but were mis-rebased into this
    one.  (Maarten)

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1463061971-19638-6-git-send-email-matthew.d.roper@intel.com

drivers/gpu/drm/i915/intel_drv.h

@@ -431,6 +431,10 @@ struct intel_crtc_wm_state {
 			/* cached plane data rate */
 			unsigned plane_data_rate[I915_MAX_PLANES];
 			unsigned plane_y_data_rate[I915_MAX_PLANES];
+
+			/* minimum block allocation */
+			uint16_t minimum_blocks[I915_MAX_PLANES];
+			uint16_t minimum_y_blocks[I915_MAX_PLANES];
 		} skl;
 	};
 

drivers/gpu/drm/i915/intel_pm.c

@@ -3067,8 +3067,8 @@ skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
 	enum pipe pipe = intel_crtc->pipe;
 	struct skl_ddb_entry *alloc = &ddb->pipe[pipe];
 	uint16_t alloc_size, start, cursor_blocks;
-	uint16_t minimum[I915_MAX_PLANES];
-	uint16_t y_minimum[I915_MAX_PLANES];
+	uint16_t *minimum = cstate->wm.skl.minimum_blocks;
+	uint16_t *y_minimum = cstate->wm.skl.minimum_y_blocks;
 	unsigned int total_data_rate;
 
 	skl_ddb_get_pipe_allocation_limits(dev, cstate, config, alloc);