[RFC 08/11] media: i2c: max9286: Move link setup to completion

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

The max9286 async notifier is a sub-notifier which does not support a
'complete' callback.

In order to properly complete the reverse channel configuration, we need
to perform operations after all remote serializers have completed their
probe.

Keep track of how many serializers have probed, and once all the
expected ones have completed its initialization:
1) Compensate the reverse channel high threshold
2) Verify that all expected control links are enabled
3) Disable i2c auto-ack

Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
---
 drivers/media/i2c/max9286.c | 32 +++++++++++++++++++++-----------
 1 file changed, 21 insertions(+), 11 deletions(-)

diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
index 3c2c1f506983..f75c97ef87a8 100644
--- a/drivers/media/i2c/max9286.c
+++ b/drivers/media/i2c/max9286.c
@@ -166,6 +166,7 @@ struct max9286_priv {
 	unsigned int nsources;
 	unsigned int source_mask;
 	unsigned int route_mask;
+	unsigned int bound_sources;
 	unsigned int csi2_data_lanes;
 	struct max9286_source sources[MAX9286_NUM_GMSL];
 	struct v4l2_async_notifier notifier;
@@ -570,6 +571,7 @@ static int max9286_notify_bound(struct v4l2_async_notifier *notifier,
 
 	source->sd = subdev;
 	src_pad = ret;
+	priv->bound_sources |= BIT(index);
 
 	ret = media_create_pad_link(&source->sd->entity, src_pad,
 				    &priv->sd.entity, index,
@@ -585,6 +587,25 @@ static int max9286_notify_bound(struct v4l2_async_notifier *notifier,
 	dev_dbg(&priv->client->dev, "Bound %s pad: %u on index %u\n",
 		subdev->name, src_pad, index);
 
+	if (priv->bound_sources != priv->source_mask)
+		return 0;
+
+	/*
+	 * All enabled sources have probed and enabled their reverse control
+	 * channels:
+	 *
+	 * - Increase the reverse channel amplitude to 170mV to accommodate the
+	 *   high threshold enabled by the serializer driver.
+	 * - Verify all configuration links are properly detected
+	 * - Disable auto-ack as communication on the control channel are now
+	 *   stable.
+	 */
+	max9286_write(priv, 0x3b, MAX9286_REV_TRF(1) | MAX9286_REV_AMP(70) |
+		      MAX9286_REV_AMP_X);
+	usleep_range(2000, 2500);
+	max9286_check_config_link(priv, priv->source_mask);
+	max9286_configure_i2c(priv, false);
+
 	return 0;
 }
 
@@ -876,11 +897,6 @@ static int max9286_setup(struct max9286_priv *priv)
 	 */
 	usleep_range(2000, 5000);
 
-	/*
-	 * Check to see if the expected configuration links are up.
-	 */
-	max9286_check_config_link(priv, priv->source_mask);
-
 	return 0;
 }
 
@@ -1042,12 +1058,6 @@ static int max9286_init(struct device *dev, void *data)
 		goto err_subdev_unregister;
 	}
 
-	/*
-	 * Re-configure I2C with local acknowledge disabled after cameras
-	 * have probed.
-	 */
-	max9286_configure_i2c(priv, false);
-
 	/* Leave the mux channels disabled until they are selected. */
 	max9286_i2c_mux_close(priv);
 
-- 
2.24.0