drm/i915: Introduce intel_calc_active_pipes()

Extract a small helper to compute the active pipes bitmask
based on the old bitmask + the crtcs in the atomic state.
I want to decouple the cdclk state entirely from the current
global state so I want to track the active pipes also inside
the (to be introduced) full cdclk state.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200120174728.21095-17-ville.syrjala@linux.intel.comReviewed-by: Imre Deak <imre.deak@intel.com>

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

@@ -14540,26 +14540,32 @@ static int hsw_mode_set_planes_workaround(struct intel_atomic_state *state)
 	return 0;
 }
 
+u8 intel_calc_active_pipes(struct intel_atomic_state *state,
+			   u8 active_pipes)
+{
+	const struct intel_crtc_state *crtc_state;
+	struct intel_crtc *crtc;
+	int i;
+
+	for_each_new_intel_crtc_in_state(state, crtc, crtc_state, i) {
+		if (crtc_state->hw.active)
+			active_pipes |= BIT(crtc->pipe);
+		else
+			active_pipes &= ~BIT(crtc->pipe);
+	}
+
+	return active_pipes;
+}
+
 static int intel_modeset_checks(struct intel_atomic_state *state)
 {
 	struct drm_i915_private *dev_priv = to_i915(state->base.dev);
-	struct intel_crtc_state *old_crtc_state, *new_crtc_state;
-	struct intel_crtc *crtc;
-	int ret, i;
+	int ret;
 
 	state->modeset = true;
-	state->active_pipes = dev_priv->active_pipes;
+	state->active_pipes = intel_calc_active_pipes(state, dev_priv->active_pipes);
 
-	for_each_oldnew_intel_crtc_in_state(state, crtc, old_crtc_state,
-					    new_crtc_state, i) {
-		if (new_crtc_state->hw.active)
-			state->active_pipes |= BIT(crtc->pipe);
-		else
-			state->active_pipes &= ~BIT(crtc->pipe);
-
-		if (old_crtc_state->hw.active != new_crtc_state->hw.active)
-			state->active_pipe_changes |= BIT(crtc->pipe);
-	}
+	state->active_pipe_changes = state->active_pipes ^ dev_priv->active_pipes;
 
 	if (state->active_pipe_changes) {
 		ret = _intel_atomic_lock_global_state(state);

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

@@ -44,6 +44,7 @@ struct drm_modeset_acquire_ctx;
 struct drm_plane;
 struct drm_plane_state;
 struct i915_ggtt_view;
+struct intel_atomic_state;
 struct intel_crtc;
 struct intel_crtc_state;
 struct intel_digital_port;
@@ -469,6 +470,8 @@ enum phy_fia {
 			     ((connector) = to_intel_connector((__state)->base.connectors[__i].ptr), \
 			     (new_connector_state) = to_intel_digital_connector_state((__state)->base.connectors[__i].new_state), 1))
 
+u8 intel_calc_active_pipes(struct intel_atomic_state *state,
+			   u8 active_pipes);
 void intel_link_compute_m_n(u16 bpp, int nlanes,
 			    int pixel_clock, int link_clock,
 			    struct intel_link_m_n *m_n,