drm/i915/display: Adjust Added Wake Time with PKG_C_LATENCY

Increase the PKG_C_LATENCY Pkg C Latency field by the added wake time.

v1: Initial version.
v2: Rebase and cosmetic changes.
v3:
- Place latency adjustment early to accommodate round-up. [Suraj]
- Modify commit description and cosmetic change. [Suraj]

WA: 22020432604
Cc: Suraj Kandpal <suraj.kandpal@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250106094408.1011063-1-animesh.manna@intel.com

Author: animesh-manna

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

@@ -2939,17 +2939,24 @@ intel_program_dpkgc_latency(struct intel_atomic_state *state)
 	}
 
 	if (fixed_refresh_rate) {
+		added_wake_time = DSB_EXE_TIME +
+			display->sagv.block_time_us;
+
 		latency = skl_watermark_max_latency(i915, 1);
+
+		/* Wa_22020432604 */
+		if ((DISPLAY_VER(display) == 20 || DISPLAY_VER(display) == 30) && !latency) {
+			latency += added_wake_time;
+			added_wake_time = 0;
+		}
+
 		/* Wa_22020299601 */
 		if ((latency && max_linetime) &&
 		    (DISPLAY_VER(display) == 20 || DISPLAY_VER(display) == 30)) {
 			latency = max_linetime * DIV_ROUND_UP(latency, max_linetime);
 		} else if (!latency) {
 			latency = LNL_PKG_C_LATENCY_MASK;
 		}
-
-		added_wake_time = DSB_EXE_TIME +
-			display->sagv.block_time_us;
 	}
 
 	clear = LNL_ADDED_WAKE_TIME_MASK | LNL_PKG_C_LATENCY_MASK;