[Intel-gfx] [PATCH 01/15] drm/i915: Allocate min dbuf blocks per bspec

[Chandra Konduru]

Properly allocate min blocks per hw requirements.

v2:
- changed helper functional param to bool, some code simplification (Ville)

Signed-off-by: Chandra Konduru <chandra.konduru at intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c |   29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index fff0c22..4d3aca0 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2959,6 +2959,31 @@ skl_get_total_relative_data_rate(struct intel_crtc *intel_crtc,
 	return total_data_rate;
 }
 
+static uint16_t
+skl_dbuf_min_alloc(const struct intel_plane_wm_parameters *p, bool y_plane)
+{
+	uint16_t min_alloc;
+
+	/* For packed formats, no y-plane, return 0 */
+	if (y_plane && !p->y_bytes_per_pixel)
+		return 0;
+
+	if (p->tiling == I915_FORMAT_MOD_Y_TILED ||
+	    p->tiling == I915_FORMAT_MOD_Yf_TILED) {
+		uint32_t min_scanlines = 8;
+		uint8_t bytes_per_pixel =
+			y_plane ? p->y_bytes_per_pixel : p->bytes_per_pixel;
+
+		min_scanlines = 32 / bytes_per_pixel;
+		min_alloc = DIV_ROUND_UP((4 * p->horiz_pixels/(y_plane ? 1 : 2) *
+			bytes_per_pixel), 512) * min_scanlines/4 + 3;
+	} else {
+		min_alloc = 8;
+	}
+
+	return min_alloc;
+}
+
 static void
 skl_allocate_pipe_ddb(struct drm_crtc *crtc,
 		      const struct intel_wm_config *config,
@@ -2999,9 +3024,9 @@ skl_allocate_pipe_ddb(struct drm_crtc *crtc,
 		if (!p->enabled)
 			continue;
 
-		minimum[plane] = 8;
+		minimum[plane] = skl_dbuf_min_alloc(p, false);   /* uv-plane/packed */
 		alloc_size -= minimum[plane];
-		y_minimum[plane] = p->y_bytes_per_pixel ? 8 : 0;
+		y_minimum[plane] = skl_dbuf_min_alloc(p, true);  /* y-plane */
 		alloc_size -= y_minimum[plane];
 	}
 
-- 
1.7.9.5