media: i2c: max9286: Use get_mbus_config for vsync config

Instead of hard-coding the vsync inversion setting, get_mbus_config()
allows to set it based on connected sources. This patch inverts
the vsync polarity if all are active low. If polarities are different
between sources, it's an error.

Signed-off-by: Hyun Kwon <hyun.kwon@xilinx.com>

drivers/media/i2c/max9286.c

@@ -556,6 +556,64 @@ static void max9286_v4l2_notifier_unregister(struct max9286_priv *priv)
 	v4l2_async_notifier_cleanup(&priv->notifier);
 }
 
+static int max9286_check_source(struct max9286_priv *priv)
+{
+	struct max9286_source *source;
+	unsigned int vsync_active = 0;
+	u8 val = MAX9286_HVEN | MAX9286_HVSRC_D14;
+	int ret;
+
+	for_each_source(priv, source) {
+		struct v4l2_mbus_pad_config mbus_config = { 0 };
+		unsigned int index = to_index(priv, source);
+
+		ret = v4l2_subdev_call(source->sd, pad, get_mbus_config,
+				       source->pad, &mbus_config);
+		if (ret) {
+			if (ret != -ENOIOCTLCMD) {
+				dev_err(&priv->client->dev,
+					"failed to get remote mbus config\n");
+				return ret;
+			}
+
+			dev_info(&priv->client->dev,
+				 "No remote mbus configuration available\n");
+			/* Assume it's active high, comaptible to GMSL */
+			vsync_active |= BIT(index);
+
+			continue;
+		}
+
+		if (mbus_config.type != V4L2_MBUS_GMSL) {
+			dev_err(&priv->client->dev,
+				"invalid mbus type %u\n", mbus_config.type);
+			return -EINVAL;
+		}
+
+		if (mbus_config.gmsl.vsync_active)
+			vsync_active |= BIT(index);
+	}
+
+	if (!vsync_active) {
+		val |= MAX9286_INVVS;
+	} else if (!(vsync_active == priv->source_mask)) {
+		dev_err(&priv->client->dev,
+			"sources have different vsync polarities %4x\n",
+			vsync_active);
+		return -EINVAL;
+	}
+
+	max9286_write(priv, 0x0c, val);
+
+	/*
+	 * Wait for 2ms to allow the link to resynchronize after the
+	 * configuration change.
+	 */
+	usleep_range(2000, 5000);
+
+	return 0;
+}
+
 static int max9286_s_stream(struct v4l2_subdev *sd, int enable)
 {
 	struct max9286_priv *priv = sd_to_max9286(sd);
@@ -565,6 +623,10 @@ static int max9286_s_stream(struct v4l2_subdev *sd, int enable)
 	int ret;
 
 	if (enable) {
+		ret = max9286_check_source(priv);
+		if (ret)
+			return ret;
+
 		/*
 		 * The frame sync between cameras is transmitted across the
 		 * reverse channel as GPIO. We must open all channels while
@@ -895,10 +957,6 @@ static int max9286_setup(struct max9286_priv *priv)
 	max9286_write(priv, 0x01, MAX9286_FSYNCMODE_INT_HIZ |
 		      MAX9286_FSYNCMETH_AUTO);
 
-	/* Enable HS/VS encoding, use D14/15 for HS/VS, invert VS. */
-	max9286_write(priv, 0x0c, MAX9286_HVEN | MAX9286_INVVS |
-		      MAX9286_HVSRC_D14);
-
 	/*
 	 * Wait for 2ms to allow the link to resynchronize after the
 	 * configuration change.