drm/i915/skl: Stage the pipe DDB allocation

To correctly flush the new DDB allocation we need to know about the pipe
allocation layout inside the DDB in order to sequence the re-allocation
to not cause a newly allocated pipe to fetch from a space that was
previously allocated to another pipe.

This patch preserves the per-pipe (start,end) allocation to be used in
the flush.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -1406,6 +1406,7 @@ static inline bool skl_ddb_entry_equal(const struct skl_ddb_entry *e1,
 }
 
 struct skl_ddb_allocation {
+	struct skl_ddb_entry pipe[I915_MAX_PIPES];
 	struct skl_ddb_entry plane[I915_MAX_PIPES][I915_MAX_PLANES];
 	struct skl_ddb_entry cursor[I915_MAX_PIPES];
 };

drivers/gpu/drm/i915/intel_pm.c

@@ -3119,13 +3119,13 @@ skl_allocate_pipe_ddb(struct drm_crtc *crtc,
 	struct drm_device *dev = crtc->dev;
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	enum pipe pipe = intel_crtc->pipe;
-	struct skl_ddb_entry alloc;
+	struct skl_ddb_entry *alloc = &ddb->pipe[pipe];
 	uint16_t alloc_size, start, cursor_blocks;
 	unsigned int total_data_rate;
 	int plane;
 
-	skl_ddb_get_pipe_allocation_limits(dev, crtc, config, params, &alloc);
-	alloc_size = skl_ddb_entry_size(&alloc);
+	skl_ddb_get_pipe_allocation_limits(dev, crtc, config, params, alloc);
+	alloc_size = skl_ddb_entry_size(alloc);
 	if (alloc_size == 0) {
 		memset(ddb->plane[pipe], 0, sizeof(ddb->plane[pipe]));
 		memset(&ddb->cursor[pipe], 0, sizeof(ddb->cursor[pipe]));
@@ -3133,11 +3133,11 @@ skl_allocate_pipe_ddb(struct drm_crtc *crtc,
 	}
 
 	cursor_blocks = skl_cursor_allocation(config);
-	ddb->cursor[pipe].start = alloc.end - cursor_blocks;
-	ddb->cursor[pipe].end = alloc.end;
+	ddb->cursor[pipe].start = alloc->end - cursor_blocks;
+	ddb->cursor[pipe].end = alloc->end;
 
 	alloc_size -= cursor_blocks;
-	alloc.end -= cursor_blocks;
+	alloc->end -= cursor_blocks;
 
 	/*
 	 * Each active plane get a portion of the remaining space, in
@@ -3147,7 +3147,7 @@ skl_allocate_pipe_ddb(struct drm_crtc *crtc,
 	 */
 	total_data_rate = skl_get_total_relative_data_rate(intel_crtc, params);
 
-	start = alloc.start;
+	start = alloc->start;
 	for (plane = 0; plane < intel_num_planes(intel_crtc); plane++) {
 		const struct intel_plane_wm_parameters *p;
 		unsigned int data_rate;