[PATCH v2 13/21] drm/i915: Extract wm latency adjustment to its own function

[Radhakrishna Sripada]

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.

Suggested-by: Matt Roper <matthew.d.roper at intel.com>
Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada at intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 88 ++++++++++++++++++---------------
 1 file changed, 48 insertions(+), 40 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index ef7553b494ea..898e56d2eaf7 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2861,15 +2861,59 @@ static void ilk_compute_wm_level(const struct drm_i915_private *dev_priv,
 	result->enable = true;
 }
 
+static void
+adjust_wm_latency(u16 wm[], int max_level, int read_latency,
+		  bool 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] */
@@ -2909,44 +2953,8 @@ 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(wm, max_level, read_latency,
+				  dev_priv->dram_info.wm_lv_0_adjust_needed);
 	} else if (IS_HASWELL(dev_priv) || IS_BROADWELL(dev_priv)) {
 		u64 sskpd = intel_uncore_read64(uncore, MCH_SSKPD);
 
-- 
2.25.1