media: adv748x: csi2: Link AFE with TXA and TXB

The ADV748x chip supports routing AFE output to either TXA or TXB.
In order to support run-time configuration of video stream path, create an
additional (not enabled) "AFE:8->TXA:0" link, and remove the IMMUTABLE flag
from existing ones.
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/i2c/adv748x/adv748x-csi2.c

@@ -27,6 +27,7 @@ static int adv748x_csi2_set_virtual_channel(struct adv748x_csi2 *tx,
  * @v4l2_dev: Video registration device
  * @src: Source subdevice to establish link
  * @src_pad: Pad number of source to link to this @tx
+ * @enable: Link enabled flag
  *
  * Ensure that the subdevice is registered against the v4l2_device, and link the
  * source pad to the sink pad of the CSI2 bus entity.
@@ -34,17 +35,11 @@ static int adv748x_csi2_set_virtual_channel(struct adv748x_csi2 *tx,
 static int adv748x_csi2_register_link(struct adv748x_csi2 *tx,
 				      struct v4l2_device *v4l2_dev,
 				      struct v4l2_subdev *src,
-				      unsigned int src_pad)
+				      unsigned int src_pad,
+				      bool enable)
 {
-	int enabled = MEDIA_LNK_FL_ENABLED;
 	int ret;
 
-	/*
-	 * Dynamic linking of the AFE is not supported.
-	 * Register the links as immutable.
-	 */
-	enabled |= MEDIA_LNK_FL_IMMUTABLE;
-
 	if (!src->v4l2_dev) {
 		ret = v4l2_device_register_subdev(v4l2_dev, src);
 		if (ret)
@@ -53,7 +48,7 @@ static int adv748x_csi2_register_link(struct adv748x_csi2 *tx,
 
 	return media_create_pad_link(&src->entity, src_pad,
 				     &tx->sd.entity, ADV748X_CSI2_SINK,
-				     enabled);
+				     enable ? MEDIA_LNK_FL_ENABLED : 0);
 }
 
 /* -----------------------------------------------------------------------------
@@ -68,25 +63,32 @@ static int adv748x_csi2_registered(struct v4l2_subdev *sd)
 {
 	struct adv748x_csi2 *tx = adv748x_sd_to_csi2(sd);
 	struct adv748x_state *state = tx->state;
+	int ret;
 
 	adv_dbg(state, "Registered %s (%s)", is_txa(tx) ? "TXA":"TXB",
 			sd->name);
 
 	/*
-	 * The adv748x hardware allows the AFE to route through the TXA, however
-	 * this is not currently supported in this driver.
+	 * Link TXA to AFE and HDMI, and TXB to AFE only as TXB cannot output
+	 * HDMI.
 	 *
-	 * Link HDMI->TXA, and AFE->TXB directly.
+	 * The HDMI->TXA link is enabled by default, as is the AFE->TXB one.
 	 */
-	if (is_txa(tx) && is_hdmi_enabled(state))
-		return adv748x_csi2_register_link(tx, sd->v4l2_dev,
-						  &state->hdmi.sd,
-						  ADV748X_HDMI_SOURCE);
-	if (is_txb(tx) && is_afe_enabled(state))
-		return adv748x_csi2_register_link(tx, sd->v4l2_dev,
-						  &state->afe.sd,
-						  ADV748X_AFE_SOURCE);
-	return 0;
+	if (is_afe_enabled(state)) {
+		ret = adv748x_csi2_register_link(tx, sd->v4l2_dev,
+						 &state->afe.sd,
+						 ADV748X_AFE_SOURCE,
+						 is_txb(tx));
+		if (ret)
+			return ret;
+	}
+
+	/* Register link to HDMI for TXA only. */
+	if (is_txb(tx) || !is_hdmi_enabled(state))
+		return 0;
+
+	return adv748x_csi2_register_link(tx, sd->v4l2_dev, &state->hdmi.sd,
+					  ADV748X_HDMI_SOURCE, true);
 }
 
 static const struct v4l2_subdev_internal_ops adv748x_csi2_internal_ops = {