drm/i915/display: update handling of FBC when VT-d active workaround

Move the handling of the disabling FBC when VT-d is active wa
as part of the intel_fbc_check_plane(). As the hw is still there,
intel_fbc_sanitize should be able to handle the state properly.

v2: update the patch description (Jani Nikula)

v3: fix the return value in wa handling (Jani Nikula)

Bspec: 21664
Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240528114826.134958-1-vinod.govindapillai@intel.com

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

@@ -1237,6 +1237,12 @@ static int intel_fbc_check_plane(struct intel_atomic_state *state,
 		return 0;
 	}
 
+	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt */
+	if (i915_vtd_active(i915) && (IS_SKYLAKE(i915) || IS_BROXTON(i915))) {
+		plane_state->no_fbc_reason = "VT-d enabled";
+		return 0;
+	}
+
 	crtc_state = intel_atomic_get_new_crtc_state(state, crtc);
 
 	if (crtc_state->hw.adjusted_mode.flags & DRM_MODE_FLAG_INTERLACE) {
@@ -1822,19 +1828,6 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *i915)
 	return 0;
 }
 
-static bool need_fbc_vtd_wa(struct drm_i915_private *i915)
-{
-	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt */
-	if (i915_vtd_active(i915) &&
-	    (IS_SKYLAKE(i915) || IS_BROXTON(i915))) {
-		drm_info(&i915->drm,
-			 "Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled\n");
-		return true;
-	}
-
-	return false;
-}
-
 void intel_fbc_add_plane(struct intel_fbc *fbc, struct intel_plane *plane)
 {
 	plane->fbc = fbc;
@@ -1880,9 +1873,6 @@ void intel_fbc_init(struct drm_i915_private *i915)
 {
 	enum intel_fbc_id fbc_id;
 
-	if (need_fbc_vtd_wa(i915))
-		DISPLAY_RUNTIME_INFO(i915)->fbc_mask = 0;
-
 	i915->display.params.enable_fbc = intel_sanitize_fbc_option(i915);
 	drm_dbg_kms(&i915->drm, "Sanitized enable_fbc value: %d\n",
 		    i915->display.params.enable_fbc);