[Intel-gfx] [PATCH i-g-t] skl_ddb_allocation: Respect the minimum number of blocks

[Damien Lespiau]

Signed-off-by: Damien Lespiau <damien.lesp...@intel.com>
---
 tests/skl_ddb_allocation.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/tests/skl_ddb_allocation.c b/tests/skl_ddb_allocation.c
index ca6b892..4d8e6d1 100644
--- a/tests/skl_ddb_allocation.c
+++ b/tests/skl_ddb_allocation.c
@@ -224,6 +224,7 @@ skl_allocate_pipe_ddb(struct drm_crtc *crtc,
        enum pipe pipe = intel_crtc->pipe;
        struct skl_ddb_entry alloc;
        uint16_t alloc_size, start, cursor_blocks;
+       uint16_t minimum[I915_MAX_PLANES];
        unsigned int total_data_rate;
        int plane;
 
@@ -242,9 +243,21 @@ skl_allocate_pipe_ddb(struct drm_crtc *crtc,
        alloc_size -= cursor_blocks;
        alloc.end -= cursor_blocks;
 
+       /* 1. Allocate the mininum required blocks for each active plane */
+       for_each_plane(pipe, plane) {
+               const struct intel_plane_wm_parameters *p;
+
+               p = &params->plane[plane];
+               if (!p->enabled)
+                       continue;
+
+               minimum[plane] = 8;
+               alloc_size -= minimum[plane];
+       }
+
        /*
-        * Each active plane get a portion of the remaining space, in
-        * proportion to the amount of data they need to fetch from memory.
+        * 2. Distribute the remaining space in proportion to the amount of
+        * data each plane needs to fetch from memory.
         *
         * FIXME: we may not allocate every single block here.
         */
@@ -266,8 +279,9 @@ skl_allocate_pipe_ddb(struct drm_crtc *crtc,
                 * promote the expression to 64 bits to avoid overflowing, the
                 * result is < available as data_rate / total_data_rate < 1
                 */
-               plane_blocks = div_u64((uint64_t)alloc_size * data_rate,
-                                      total_data_rate);
+               plane_blocks = minimum[plane];
+               plane_blocks += div_u64((uint64_t)alloc_size * data_rate,
+                                       total_data_rate);
 
                ddb->plane[pipe][plane].start = start;
                ddb->plane[pipe][plane].end = start + plane_blocks;
-- 
1.8.3.1

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