drm/vc4: kms: Split the HVS muxing check in a separate function

The code that assigns HVS channels during atomic_check is starting to grow
a bit big, let's move it into a separate function.
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
Reviewed-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20201105135656.383350-5-maxime@cerno.tech

drivers/gpu/drm/vc4/vc4_kms.c

@@ -662,13 +662,13 @@ static int vc4_load_tracker_obj_init(struct vc4_dev *vc4)
 	return drmm_add_action_or_reset(&vc4->base, vc4_load_tracker_obj_fini, NULL);
 }
 
-static int
-vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
+static int vc4_pv_muxing_atomic_check(struct drm_device *dev,
+				      struct drm_atomic_state *state)
 {
 	unsigned long unassigned_channels = GENMASK(HVS_NUM_CHANNELS - 1, 0);
 	struct drm_crtc_state *old_crtc_state, *new_crtc_state;
 	struct drm_crtc *crtc;
-	int i, ret;
+	unsigned int i;
 
 	/*
 	 * Since the HVS FIFOs are shared across all the pixelvalves and
@@ -741,6 +741,18 @@ vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
 		}
 	}
 
+	return 0;
+}
+
+static int
+vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
+{
+	int ret;
+
+	ret = vc4_pv_muxing_atomic_check(dev, state);
+	if (ret)
+		return ret;
+
 	ret = vc4_ctm_atomic_check(dev, state);
 	if (ret < 0)
 		return ret;