drm/i915/vrr: drop window2_delay member from i915

The window2_delay member has been functionally unused (always set to 0)
since it was added in commit bb265dbd ("drm/i915/xelpd: Add VRR
guardband for VRR CTL"). Replace it with a FIXME comment.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/036955dc2c4c2d2b2d89555e473d91ce1be10395.1661346845.git.jani.nikula@intel.com

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

@@ -8686,8 +8686,6 @@ int intel_modeset_init_noirq(struct drm_i915_private *i915)
 	i915->flip_wq = alloc_workqueue("i915_flip", WQ_HIGHPRI |
 					WQ_UNBOUND, WQ_UNBOUND_MAX_ACTIVE);
 
-	i915->window2_delay = 0; /* No DSB so no window2 delay */
-
 	intel_mode_config_init(i915);
 
 	ret = intel_cdclk_init(i915);

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

@@ -142,11 +142,16 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
 	 * For XE_LPD+, we use guardband and pipeline override
 	 * is deprecated.
 	 */
-	if (DISPLAY_VER(i915) >= 13)
+	if (DISPLAY_VER(i915) >= 13) {
+		/*
+		 * FIXME: Subtract Window2 delay from below value.
+		 *
+		 * Window2 specifies time required to program DSB (Window2) in
+		 * number of scan lines. Assuming 0 for no DSB.
+		 */
 		crtc_state->vrr.guardband =
-			crtc_state->vrr.vmin - adjusted_mode->crtc_vdisplay -
-			i915->window2_delay;
-	else
+			crtc_state->vrr.vmin - adjusted_mode->crtc_vdisplay;
+	} else {
 		/*
 		 * FIXME: s/4/framestart_delay/ to get consistent
 		 * earliest/latest points for register latching regardless
@@ -159,6 +164,7 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
 		 */
 		crtc_state->vrr.pipeline_full =
 			min(255, crtc_state->vrr.vmin - adjusted_mode->crtc_vdisplay - 4 - 1);
+	}
 
 	crtc_state->mode_flags |= I915_MODE_FLAG_VRR;
 }

drivers/gpu/drm/i915/i915_drv.h

@@ -512,9 +512,6 @@ struct drm_i915_private {
 		struct file *mmap_singleton;
 	} gem;
 
-	/* Window2 specifies time required to program DSB (Window2) in number of scan lines */
-	u8 window2_delay;
-
 	u8 pch_ssc_use;
 
 	/* For i915gm/i945gm vblank irq workaround */