drm/i915: Extract wm latency adjustment to its own function

Watermark latency is adjusted in cases when latency is 0us for level
greater than 1, the subsequent levels are disabled. Extract this logic
into its own function.

v2: Pass dev_priv to the extracted function(MattR)
Suggested-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220818234202.451742-14-radhakrishna.sripada@intel.com

drivers/gpu/drm/i915/intel_pm.c

@@ -2862,15 +2862,60 @@ static void ilk_compute_wm_level(const struct drm_i915_private *dev_priv,
 	result->enable = true;
 }
 
+static void
+adjust_wm_latency(struct drm_i915_private *i915,
+		  u16 wm[], int max_level, int read_latency)
+{
+	bool wm_lv_0_adjust_needed = i915->dram_info.wm_lv_0_adjust_needed;
+	int i, level;
+
+	/*
+	 * If a level n (n > 1) has a 0us latency, all levels m (m >= n)
+	 * need to be disabled. We make sure to sanitize the values out
+	 * of the punit to satisfy this requirement.
+	 */
+	for (level = 1; level <= max_level; level++) {
+		if (wm[level] == 0) {
+			for (i = level + 1; i <= max_level; i++)
+				wm[i] = 0;
+
+			max_level = level - 1;
+			break;
+		}
+	}
+
+	/*
+	 * WaWmMemoryReadLatency
+	 *
+	 * punit doesn't take into account the read latency so we need
+	 * to add proper adjustement to each valid level we retrieve
+	 * from the punit when level 0 response data is 0us.
+	 */
+	if (wm[0] == 0) {
+		for (level = 0; level <= max_level; level++)
+			wm[level] += read_latency;
+	}
+
+	/*
+	 * WA Level-0 adjustment for 16GB DIMMs: SKL+
+	 * If we could not get dimm info enable this WA to prevent from
+	 * any underrun. If not able to get Dimm info assume 16GB dimm
+	 * to avoid any underrun.
+	 */
+	if (wm_lv_0_adjust_needed)
+		wm[0] += 1;
+}
+
 static void intel_read_wm_latency(struct drm_i915_private *dev_priv,
 				  u16 wm[])
 {
 	struct intel_uncore *uncore = &dev_priv->uncore;
 
 	if (DISPLAY_VER(dev_priv) >= 9) {
+		int read_latency = DISPLAY_VER(dev_priv) >= 12 ? 3 : 2;
 		u32 val;
-		int ret, i;
-		int level, max_level = ilk_wm_max_level(dev_priv);
+		int ret;
+		int max_level = ilk_wm_max_level(dev_priv);
 		int mult = IS_DG2(dev_priv) ? 2 : 1;
 
 		/* read the first set of memory latencies[0:3] */
@@ -2910,44 +2955,7 @@ static void intel_read_wm_latency(struct drm_i915_private *dev_priv,
 		wm[7] = ((val >> GEN9_MEM_LATENCY_LEVEL_3_7_SHIFT) &
 				GEN9_MEM_LATENCY_LEVEL_MASK) * mult;
 
-		/*
-		 * If a level n (n > 1) has a 0us latency, all levels m (m >= n)
-		 * need to be disabled. We make sure to sanitize the values out
-		 * of the punit to satisfy this requirement.
-		 */
-		for (level = 1; level <= max_level; level++) {
-			if (wm[level] == 0) {
-				for (i = level + 1; i <= max_level; i++)
-					wm[i] = 0;
-
-				max_level = level - 1;
-
-				break;
-			}
-		}
-
-		/*
-		 * WaWmMemoryReadLatency
-		 *
-		 * punit doesn't take into account the read latency so we need
-		 * to add proper adjustement to each valid level we retrieve
-		 * from the punit when level 0 response data is 0us.
-		 */
-		if (wm[0] == 0) {
-			u8 adjust = DISPLAY_VER(dev_priv) >= 12 ? 3 : 2;
-
-			for (level = 0; level <= max_level; level++)
-				wm[level] += adjust;
-		}
-
-		/*
-		 * WA Level-0 adjustment for 16GB DIMMs: SKL+
-		 * If we could not get dimm info enable this WA to prevent from
-		 * any underrun. If not able to get Dimm info assume 16GB dimm
-		 * to avoid any underrun.
-		 */
-		if (dev_priv->dram_info.wm_lv_0_adjust_needed)
-			wm[0] += 1;
+		adjust_wm_latency(dev_priv, wm, max_level, read_latency);
 	} else if (IS_HASWELL(dev_priv) || IS_BROADWELL(dev_priv)) {
 		u64 sskpd = intel_uncore_read64(uncore, MCH_SSKPD);