drm/i915/display: Extract code required to calculate max qgv/psf gv point

We need that in order to force disable SAGV in next patch.
Also it is beneficial to separate that code, as in majority cases,
when SAGV is enabled, we don't even need those calculations.
Also we probably need to determine max PSF GV point as well, however
currently we don't do that when we disable SAGV, which might be
actually causing some issues in that case.

v2: - Introduce helper adl_qgv_bw(counterpart to adl_psf_bw)
      (Ville Syrjälä)
    - Don't restrict psf gv points for SAGV disable case
      (Ville Syrjälä)
v3: - Update icl_max_bw_qgv_point_mask to return max qgv point
      mask (Vinod)
v4: - Minor changes in icl_find_qgv_points (Vinod)
v5: - use max_bw_point instead of max_bw_point_mask (stan)
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Signed-off-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240405113533.338553-3-vinod.govindapillai@intel.com

drivers/gpu/drm/i915/display/intel_bw.c

@@ -661,6 +661,22 @@ static unsigned int adl_psf_bw(struct drm_i915_private *dev_priv,
 	return bi->psf_bw[psf_gv_point];
 }
 
+static unsigned int icl_qgv_bw(struct drm_i915_private *i915,
+			       int num_active_planes, int qgv_point)
+{
+	unsigned int idx;
+
+	if (DISPLAY_VER(i915) >= 12)
+		idx = tgl_max_bw_index(i915, num_active_planes, qgv_point);
+	else
+		idx = icl_max_bw_index(i915, num_active_planes, qgv_point);
+
+	if (idx >= ARRAY_SIZE(i915->display.bw.max))
+		return 0;
+
+	return i915->display.bw.max[idx].deratedbw[qgv_point];
+}
+
 void intel_bw_init_hw(struct drm_i915_private *dev_priv)
 {
 	if (!HAS_DISPLAY(dev_priv))
@@ -806,6 +822,35 @@ intel_atomic_get_bw_state(struct intel_atomic_state *state)
 	return to_intel_bw_state(bw_state);
 }
 
+static unsigned int icl_max_bw_qgv_point_mask(struct drm_i915_private *i915,
+					      int num_active_planes)
+{
+	unsigned int num_qgv_points = i915->display.bw.max[0].num_qgv_points;
+	unsigned int max_bw_point = 0;
+	unsigned int max_bw = 0;
+	int i;
+
+	for (i = 0; i < num_qgv_points; i++) {
+		unsigned int max_data_rate =
+			icl_qgv_bw(i915, num_active_planes, i);
+
+		/*
+		 * We need to know which qgv point gives us
+		 * maximum bandwidth in order to disable SAGV
+		 * if we find that we exceed SAGV block time
+		 * with watermarks. By that moment we already
+		 * have those, as it is calculated earlier in
+		 * intel_atomic_check,
+		 */
+		if (max_data_rate > max_bw) {
+			max_bw_point = BIT(i);
+			max_bw = max_data_rate;
+		}
+	}
+
+	return max_bw_point;
+}
+
 static int mtl_find_qgv_points(struct drm_i915_private *i915,
 			       unsigned int data_rate,
 			       unsigned int num_active_planes,
@@ -883,8 +928,6 @@ static int icl_find_qgv_points(struct drm_i915_private *i915,
 			       const struct intel_bw_state *old_bw_state,
 			       struct intel_bw_state *new_bw_state)
 {
-	unsigned int max_bw_point = 0;
-	unsigned int max_bw = 0;
 	unsigned int num_psf_gv_points = i915->display.bw.max[0].num_psf_gv_points;
 	unsigned int num_qgv_points = i915->display.bw.max[0].num_qgv_points;
 	u16 psf_points = 0;
@@ -897,31 +940,8 @@ static int icl_find_qgv_points(struct drm_i915_private *i915,
 		return ret;
 
 	for (i = 0; i < num_qgv_points; i++) {
-		unsigned int idx;
-		unsigned int max_data_rate;
-
-		if (DISPLAY_VER(i915) >= 12)
-			idx = tgl_max_bw_index(i915, num_active_planes, i);
-		else
-			idx = icl_max_bw_index(i915, num_active_planes, i);
-
-		if (idx >= ARRAY_SIZE(i915->display.bw.max))
-			continue;
-
-		max_data_rate = i915->display.bw.max[idx].deratedbw[i];
-
-		/*
-		 * We need to know which qgv point gives us
-		 * maximum bandwidth in order to disable SAGV
-		 * if we find that we exceed SAGV block time
-		 * with watermarks. By that moment we already
-		 * have those, as it is calculated earlier in
-		 * intel_atomic_check,
-		 */
-		if (max_data_rate > max_bw) {
-			max_bw_point = i;
-			max_bw = max_data_rate;
-		}
+		unsigned int max_data_rate = icl_qgv_bw(i915,
+							num_active_planes, i);
 		if (max_data_rate >= data_rate)
 			qgv_points |= BIT(i);
 
@@ -965,9 +985,9 @@ static int icl_find_qgv_points(struct drm_i915_private *i915,
 	 * cause.
 	 */
 	if (!intel_can_enable_sagv(i915, new_bw_state)) {
-		qgv_points = BIT(max_bw_point);
-		drm_dbg_kms(&i915->drm, "No SAGV, using single QGV point %d\n",
-			    max_bw_point);
+		qgv_points = icl_max_bw_qgv_point_mask(i915, num_active_planes);
+		drm_dbg_kms(&i915->drm, "No SAGV, using single QGV point mask 0x%x\n",
+			    qgv_points);
 	}
 
 	/*