drm/i915: modify max_bw to return index to intel_bw_info

MTL uses the peak BW of a QGV point to lock the required QGV
point instead of the QGV index. Instead of passing the deratedbw
of the selected bw_info, return the index to the selected
bw_info so that either deratedbw or peakbw can be used based on
the platform.

v2: use idx to store index returned by max_bw_index functions

v3: return UINT_MAX in icl_max_bw_index in case no match found

v3: check idx >= ARRAY_SIZE
Signed-off-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230606093509.221709-6-vinod.govindapillai@intel.com

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

@@ -593,8 +593,8 @@ static void dg2_get_bw_info(struct drm_i915_private *i915)
 	i915->display.sagv.status = I915_SAGV_NOT_CONTROLLED;
 }
 
-static unsigned int icl_max_bw(struct drm_i915_private *dev_priv,
-			       int num_planes, int qgv_point)
+static unsigned int icl_max_bw_index(struct drm_i915_private *dev_priv,
+				     int num_planes, int qgv_point)
 {
 	int i;
 
@@ -615,14 +615,14 @@ static unsigned int icl_max_bw(struct drm_i915_private *dev_priv,
 			return UINT_MAX;
 
 		if (num_planes >= bi->num_planes)
-			return bi->deratedbw[qgv_point];
+			return i;
 	}
 
-	return 0;
+	return UINT_MAX;
 }
 
-static unsigned int tgl_max_bw(struct drm_i915_private *dev_priv,
-			       int num_planes, int qgv_point)
+static unsigned int tgl_max_bw_index(struct drm_i915_private *dev_priv,
+				     int num_planes, int qgv_point)
 {
 	int i;
 
@@ -643,10 +643,10 @@ static unsigned int tgl_max_bw(struct drm_i915_private *dev_priv,
 			return UINT_MAX;
 
 		if (num_planes <= bi->num_planes)
-			return bi->deratedbw[qgv_point];
+			return i;
 	}
 
-	return dev_priv->display.bw.max[0].deratedbw[qgv_point];
+	return 0;
 }
 
 static unsigned int adl_psf_bw(struct drm_i915_private *dev_priv,
@@ -823,12 +823,19 @@ 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) > 11)
-			max_data_rate = tgl_max_bw(i915, num_active_planes, i);
+			idx = tgl_max_bw_index(i915, num_active_planes, i);
 		else
-			max_data_rate = icl_max_bw(i915, num_active_planes, i);
+			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