[Intel-gfx] [PATCH 3/7] drm/i915/skl+: calculate ddb minimum allocation

[Shobhit Kumar]

From: "Kumar, Mahesh" <mahesh1.kumar at intel.com>

don't always use 8 ddb as minimum, instead calculate using proper
algorithm.

Signed-off-by: Kumar, Mahesh <mahesh1.kumar at intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 57 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 55 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index d33c4ff..64b39ec 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2994,6 +2994,59 @@ skl_get_total_relative_data_rate(const struct intel_crtc_state *cstate)
 	return total_data_rate;
 }
 
+static uint16_t
+skl_ddb_min_alloc(const struct intel_crtc *crtc,
+		const struct drm_plane *plane, int y)
+{
+	struct drm_framebuffer *fb = plane->state->fb;
+	struct intel_plane_state *pstate = to_intel_plane_state(plane->state);
+	uint16_t min_alloc;
+	uint32_t src_w, src_h;
+
+	/* For packed formats, no y-plane, return 0 */
+	if (y && !(fb->pixel_format == DRM_FORMAT_NV12))
+		return 0;
+
+	if (drm_rect_width(&pstate->src)) {
+		src_w = drm_rect_width(&pstate->src) >> 16;
+		src_h = drm_rect_height(&pstate->src) >> 16;
+	} else {
+		src_w = crtc->config->pipe_src_w;
+		src_h = crtc->config->pipe_src_h;
+	}
+
+	if (intel_rotation_90_or_270(plane->state->rotation))
+		swap(src_w, src_h);
+
+	if (fb->modifier[0] == I915_FORMAT_MOD_Y_TILED ||
+	    fb->modifier[0] == I915_FORMAT_MOD_Yf_TILED) {
+		uint32_t min_scanlines = 8;
+		uint8_t bytes_per_pixel =
+			y ? drm_format_plane_cpp(fb->pixel_format, 1) :
+				drm_format_plane_cpp(fb->pixel_format, 0);
+
+		if (intel_rotation_90_or_270(plane->state->rotation)) {
+			switch (bytes_per_pixel) {
+			case 1:
+				min_scanlines = 32;
+				break;
+			case 2:
+				min_scanlines = 16;
+				break;
+			case 8:
+				WARN(1, "Unsupported pixel depth for rotation");
+			}
+		}
+		min_alloc = DIV_ROUND_UP((4 * src_w / (y ? 1 : 2) *
+				bytes_per_pixel), 512) * min_scanlines/4 + 3;
+	} else {
+		min_alloc = 8;
+	}
+
+	return min_alloc;
+}
+
+
 static void
 skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
 		      struct skl_ddb_allocation *ddb /* out */)
@@ -3038,9 +3091,9 @@ skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
 		if (plane->type == DRM_PLANE_TYPE_CURSOR)
 			continue;
 
-		minimum[id] = 8;
+		minimum[id] = skl_ddb_min_alloc(intel_crtc, plane, 0);
 		alloc_size -= minimum[id];
-		y_minimum[id] = (fb->pixel_format == DRM_FORMAT_NV12) ? 8 : 0;
+		y_minimum[id] = skl_ddb_min_alloc(intel_crtc, plane, 1);
 		alloc_size -= y_minimum[id];
 	}
 
-- 
2.4.3