[Intel-gfx] [PATCH v1] drm/i915: Restrict qgv points which don't have enough bandwidth.

[Stanislav Lisovskiy]

According to BSpec 53998, we should try to
restrict qgv points, which can't provide
enough bandwidth for desired display configuration.

Currently we are just comparing against all of
those and take minimum(worst case).

Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
---
 drivers/gpu/drm/i915/display/intel_bw.c | 57 +++++++++++++++++++++++--
 drivers/gpu/drm/i915/i915_reg.h         |  1 +
 2 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_bw.c b/drivers/gpu/drm/i915/display/intel_bw.c
index cd58e47ab7b2..f65e4aec6ecc 100644
--- a/drivers/gpu/drm/i915/display/intel_bw.c
+++ b/drivers/gpu/drm/i915/display/intel_bw.c
@@ -90,6 +90,25 @@ static int icl_pcode_read_qgv_point_info(struct drm_i915_private *dev_priv,
 	return 0;
 }
 
+static int icl_pcode_restrict_qgv_points(struct drm_i915_private *dev_priv, u32 points_mask)
+{
+	int ret;
+
+	/* bspec says to keep retrying for at least 1 ms */
+	ret = skl_pcode_request(dev_priv, ICL_PCODE_SAGV_DE_MEM_SS_CONFIG,
+				points_mask,
+				0xff, points_mask,
+				1);
+
+	if (ret < 0) {
+		DRM_ERROR("Failed to disable qgv points (%d)\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+
 static int icl_get_qgv_points(struct drm_i915_private *dev_priv,
 			      struct intel_qgv_info *qi)
 {
@@ -354,7 +373,9 @@ int intel_bw_atomic_check(struct intel_atomic_state *state)
 	unsigned int data_rate, max_data_rate;
 	unsigned int num_active_planes;
 	struct intel_crtc *crtc;
-	int i;
+	int i, ret;
+	struct intel_qgv_info qi = {};
+	u32 points_mask = 0;
 
 	/* FIXME earlier gens need some checks too */
 	if (INTEL_GEN(dev_priv) < 11)
@@ -398,10 +419,40 @@ int intel_bw_atomic_check(struct intel_atomic_state *state)
 	data_rate = intel_bw_data_rate(dev_priv, bw_state);
 	num_active_planes = intel_bw_num_active_planes(dev_priv, bw_state);
 
-	max_data_rate = intel_max_data_rate(dev_priv, num_active_planes);
-
 	data_rate = DIV_ROUND_UP(data_rate, 1000);
 
+	ret = icl_get_qgv_points(dev_priv, &qi);
+	if (ret < 0) {
+		goto fallback;
+	}
+
+	for (i = 0; i < qi.num_points; i++) {
+		max_data_rate = icl_max_bw(dev_priv, num_active_planes, i);
+		if (max_data_rate < data_rate) {
+			DRM_DEBUG_KMS("QGV point %d: max bw %d required %d restricted\n",
+				      i, max_data_rate, data_rate);
+			points_mask |= 1 << i;
+		} else
+			DRM_DEBUG_KMS("QGV point %d: max bw %d required %d unrestricted\n",
+				      i, max_data_rate, data_rate);
+	}
+
+	if (points_mask >= ((1 << qi.num_points) - 1)) {
+		DRM_DEBUG_KMS("Could not find any suitable QGV points\n");
+		return -EINVAL;
+	}
+
+	ret = icl_pcode_restrict_qgv_points(dev_priv, points_mask);
+	if (ret < 0) {
+		DRM_DEBUG_KMS("Could not restrict required gqv points(%d)\n", ret);
+		goto fallback;
+	}
+
+	return 0;
+
+fallback:
+	max_data_rate = intel_max_data_rate(dev_priv, num_active_planes);
+
 	if (data_rate > max_data_rate) {
 		DRM_DEBUG_KMS("Bandwidth %u MB/s exceeds max available %d MB/s (%d active planes)\n",
 			      data_rate, max_data_rate, num_active_planes);
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index bf37ecebc82f..df26d15dcbb5 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -8845,6 +8845,7 @@ enum {
 #define   ICL_PCODE_MEM_SUBSYSYSTEM_INFO	0xd
 #define     ICL_PCODE_MEM_SS_READ_GLOBAL_INFO	(0x0 << 8)
 #define     ICL_PCODE_MEM_SS_READ_QGV_POINT_INFO(point)	(((point) << 16) | (0x1 << 8))
+#define   ICL_PCODE_SAGV_DE_MEM_SS_CONFIG	0xe
 #define   GEN6_PCODE_READ_D_COMP		0x10
 #define   GEN6_PCODE_WRITE_D_COMP		0x11
 #define   HSW_PCODE_DE_WRITE_FREQ_REQ		0x17
-- 
2.17.1