[RFC 4/4] media: i2c: gmsl: Defer camera intialization

[Jacopo Mondi <jacopo+renesas@jmondi.org>]

Use the post_register() callback to defer the bulk of the camera
modules initialization. The deserializer driver waits for all the
registered camera to probe, increases its channel amplitude and the
calls the subdevice post_register() operation that completes the
initialization procedure.

Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
---
 drivers/media/i2c/max9286.c | 21 ++++++++--
 drivers/media/i2c/rdacm20.c | 81 +++++++++++++++++++++----------------
 2 files changed, 65 insertions(+), 37 deletions(-)

diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
index 34582199452b..2c9cbb3079ac 100644
--- a/drivers/media/i2c/max9286.c
+++ b/drivers/media/i2c/max9286.c
@@ -567,17 +567,31 @@ static int max9286_notify_bound(struct v4l2_async_notifier *notifier,
 	if (priv->bound_sources != priv->source_mask)
 		return 0;
 
+	/*
+	 * Once all cameras have probed, increase the channel amplitude
+	 * to compensate for the remote noise immunity threshold and call
+	 * the camera post_register operation to complete initialization with
+	 * noise immunity enabled.
+	 */
+	max9286_reverse_channel_setup(priv, MAX9286_REV_AMP_HIGH);
+	for_each_source(priv, source) {
+		ret = v4l2_subdev_call(source->sd, core, post_register);
+		if (ret) {
+			dev_err(&priv->client->dev,
+					"Failed to initialize camera device %u\n",
+					index);
+			return ret;
+		}
+	}
+
 	/*
 	 * All enabled sources have probed and enabled their reverse control
 	 * channels:
 	 *
-	 * - Increase the reverse channel amplitude to compensate for the
-	 *   remote ends high threshold
 	 * - Verify all configuration links are properly detected
 	 * - Disable auto-ack as communication on the control channel are now
 	 *   stable.
 	 */
-	max9286_reverse_channel_setup(priv, MAX9286_REV_AMP_HIGH);
 	max9286_check_config_link(priv, priv->source_mask);
 	max9286_configure_i2c(priv, false);
 
@@ -630,6 +644,7 @@ static int max9286_v4l2_notifier_register(struct max9286_priv *priv)
 	}
 
 	priv->notifier.ops = &max9286_notify_ops;
+	priv->notifier.flags |= V4L2_ASYNC_NOTIFIER_SKIP_POST_REGISTER;
 
 	ret = v4l2_async_subdev_notifier_register(&priv->sd, &priv->notifier);
 	if (ret) {
diff --git a/drivers/media/i2c/rdacm20.c b/drivers/media/i2c/rdacm20.c
index cb725c2778c0..9f6ccfc9a78a 100644
--- a/drivers/media/i2c/rdacm20.c
+++ b/drivers/media/i2c/rdacm20.c
@@ -435,44 +435,12 @@ static int rdacm20_get_fmt(struct v4l2_subdev *sd,
 	return 0;
 }
 
-static const struct v4l2_subdev_video_ops rdacm20_video_ops = {
-	.s_stream	= rdacm20_s_stream,
-};
-
-static const struct v4l2_subdev_pad_ops rdacm20_subdev_pad_ops = {
-	.enum_mbus_code = rdacm20_enum_mbus_code,
-	.get_fmt	= rdacm20_get_fmt,
-	.set_fmt	= rdacm20_get_fmt,
-};
-
-static const struct v4l2_subdev_ops rdacm20_subdev_ops = {
-	.video		= &rdacm20_video_ops,
-	.pad		= &rdacm20_subdev_pad_ops,
-};
-
-static int rdacm20_initialize(struct rdacm20_device *dev)
+static int rdacm20_post_register(struct v4l2_subdev *sd)
 {
+	struct rdacm20_device *dev = sd_to_rdacm20(sd);
 	unsigned int retry = 3;
 	int ret;
 
-	max9271_wake_up(&dev->serializer);
-
-	/* Serial link disabled during config as it needs a valid pixel clock. */
-	ret = max9271_set_serial_link(&dev->serializer, false);
-	if (ret)
-		return ret;
-
-	/*
-	 *  Ensure that we have a good link configuration before attempting to
-	 *  identify the device.
-	 */
-	ret = max9271_configure_i2c(&dev->serializer,
-				    MAX9271_I2CSLVSH_469NS_234NS |
-				    MAX9271_I2CSLVTO_1024US |
-				    MAX9271_I2CMSTBT_105KBPS);
-	if (ret)
-		return ret;
-
 	/*
 	 * Hold OV10635 in reset during max9271 configuration. The reset signal
 	 * has to be asserted for at least 200 microseconds.
@@ -549,6 +517,51 @@ static int rdacm20_initialize(struct rdacm20_device *dev)
 
 	dev_info(dev->dev, "Identified RDACM20 camera module\n");
 
+	return 0;
+}
+
+static const struct v4l2_subdev_video_ops rdacm20_video_ops = {
+	.s_stream	= rdacm20_s_stream,
+};
+
+static const struct v4l2_subdev_pad_ops rdacm20_subdev_pad_ops = {
+	.enum_mbus_code = rdacm20_enum_mbus_code,
+	.get_fmt	= rdacm20_get_fmt,
+	.set_fmt	= rdacm20_get_fmt,
+};
+
+static const struct v4l2_subdev_core_ops rdacm20_core_ops = {
+	.post_register	= rdacm20_post_register,
+};
+
+static const struct v4l2_subdev_ops rdacm20_subdev_ops = {
+	.core		= &rdacm20_core_ops,
+	.video		= &rdacm20_video_ops,
+	.pad		= &rdacm20_subdev_pad_ops,
+};
+
+static int rdacm20_initialize(struct rdacm20_device *dev)
+{
+	int ret;
+
+	max9271_wake_up(&dev->serializer);
+
+	/* Serial link disabled during config as it needs a valid pixel clock. */
+	ret = max9271_set_serial_link(&dev->serializer, false);
+	if (ret)
+		return ret;
+
+	/*
+	 *  Ensure that we have a good link configuration before attempting to
+	 *  identify the device.
+	 */
+	ret = max9271_configure_i2c(&dev->serializer,
+				    MAX9271_I2CSLVSH_469NS_234NS |
+				    MAX9271_I2CSLVTO_1024US |
+				    MAX9271_I2CMSTBT_105KBPS);
+	if (ret)
+		return ret;
+
 	/*
 	 * Set reverse channel high threshold to increase noise immunity.
 	 *
-- 
2.31.1