diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
index 051a02ac01a4..614f319d754e 100644
--- a/drivers/gpu/drm/i915/display/skl_watermark.c
+++ b/drivers/gpu/drm/i915/display/skl_watermark.c
@@ -443,12 +443,35 @@ static int intel_compute_sagv_mask(struct intel_atomic_state *state)
 
 	for_each_new_intel_crtc_in_state(state, crtc,
 					 new_crtc_state, i) {
+		struct skl_pipe_wm *pipe_wm = &new_crtc_state->wm.skl.optimal;
+
 		new_bw_state = intel_atomic_get_bw_state(state);
 		if (IS_ERR(new_bw_state))
 			return PTR_ERR(new_bw_state);
 
 		old_bw_state = intel_atomic_get_old_bw_state(state);
 
+		/*
+		 * We store use_sagv_wm in the crtc state rather than relying on
+		 * that bw state since we have no convenient way to get at the
+		 * latter from the plane commit hooks (especially in the legacy
+		 * cursor case).
+		 *
+		 * drm_atomic_check_only() gets upset if we pull more crtcs
+		 * into the state, so we have to calculate this based on the
+		 * individual intel_crtc_can_enable_sagv() rather than
+		 * the overall intel_can_enable_sagv(). Otherwise the
+		 * crtcs not included in the commit would not switch to the
+		 * SAGV watermarks when we are about to enable SAGV, and that
+		 * would lead to underruns. This does mean extra power draw
+		 * when only a subset of the crtcs are blocking SAGV as the
+		 * other crtcs can't be allowed to use the more optimal
+		 * normal (ie. non-SAGV) watermarks.
+		 */
+		pipe_wm->use_sagv_wm = !HAS_HW_SAGV_WM(i915) &&
+			DISPLAY_VER(i915) >= 12 &&
+			intel_crtc_can_enable_sagv(new_crtc_state);
+
 		if (intel_crtc_can_enable_sagv(new_crtc_state))
 			new_bw_state->pipe_sagv_reject &= ~BIT(crtc->pipe);
 		else
@@ -478,21 +501,6 @@ static int intel_compute_sagv_mask(struct intel_atomic_state *state)
 			return ret;
 	}
 
-	for_each_new_intel_crtc_in_state(state, crtc,
-					 new_crtc_state, i) {
-		struct skl_pipe_wm *pipe_wm = &new_crtc_state->wm.skl.optimal;
-
-		/*
-		 * We store use_sagv_wm in the crtc state rather than relying on
-		 * that bw state since we have no convenient way to get at the
-		 * latter from the plane commit hooks (especially in the legacy
-		 * cursor case)
-		 */
-		pipe_wm->use_sagv_wm = !HAS_HW_SAGV_WM(i915) &&
-			DISPLAY_VER(i915) >= 12 &&
-			intel_can_enable_sagv(i915, new_bw_state);
-	}
-
 	return 0;
 }