Patch "media: sun6i-mipi-csi2: Register async subdev with no sensor attached" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    media: sun6i-mipi-csi2: Register async subdev with no sensor attached

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     media-sun6i-mipi-csi2-register-async-subdev-with-no-.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 932fd79aff4ce60805564297f096fe5f07bfb572
Author: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx>
Date:   Fri Sep 9 14:39:53 2022 +0100

    media: sun6i-mipi-csi2: Register async subdev with no sensor attached
    
    [ Upstream commit 67182951f1dde5a88479cf8befee5f32ea014a49 ]
    
    This allows the device to probe and register its async subdev without
    a sensor attached.
    
    The rationale is that the parent driver might otherwise wait for the
    subdev to be registered when it should be available (from the fwnode
    graph endpoint perspective). This is generally not problematic when
    the MIPI CSI-2 bridge is the only device attached to the parent, but
    in the case of a CSI controller that can feed from both MIPI CSI-2
    and parallel, it would prevent using the parallel sensor due to the
    parent waiting for the MIPI CSI-2 subdev to register.
    
    Fixes: af54b4f4c17f ("media: sunxi: Add support for the A31 MIPI CSI-2 controller")
    Signed-off-by: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx>
    Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
    Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/media/platform/sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.c b/drivers/media/platform/sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.c
index 340380a5f66f..484ac5f054d5 100644
--- a/drivers/media/platform/sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.c
+++ b/drivers/media/platform/sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.c
@@ -498,6 +498,7 @@ static int sun6i_mipi_csi2_bridge_setup(struct sun6i_mipi_csi2_device *csi2_dev)
 	struct v4l2_async_notifier *notifier = &bridge->notifier;
 	struct media_pad *pads = bridge->pads;
 	struct device *dev = csi2_dev->dev;
+	bool notifier_registered = false;
 	int ret;
 
 	mutex_init(&bridge->lock);
@@ -535,12 +536,17 @@ static int sun6i_mipi_csi2_bridge_setup(struct sun6i_mipi_csi2_device *csi2_dev)
 	notifier->ops = &sun6i_mipi_csi2_notifier_ops;
 
 	ret = sun6i_mipi_csi2_bridge_source_setup(csi2_dev);
-	if (ret)
+	if (ret && ret != -ENODEV)
 		goto error_v4l2_notifier_cleanup;
 
-	ret = v4l2_async_subdev_nf_register(subdev, notifier);
-	if (ret < 0)
-		goto error_v4l2_notifier_cleanup;
+	/* Only register the notifier when a sensor is connected. */
+	if (ret != -ENODEV) {
+		ret = v4l2_async_subdev_nf_register(subdev, notifier);
+		if (ret < 0)
+			goto error_v4l2_notifier_cleanup;
+
+		notifier_registered = true;
+	}
 
 	/* V4L2 Subdev */
 
@@ -551,7 +557,8 @@ static int sun6i_mipi_csi2_bridge_setup(struct sun6i_mipi_csi2_device *csi2_dev)
 	return 0;
 
 error_v4l2_notifier_unregister:
-	v4l2_async_nf_unregister(notifier);
+	if (notifier_registered)
+		v4l2_async_nf_unregister(notifier);
 
 error_v4l2_notifier_cleanup:
 	v4l2_async_nf_cleanup(notifier);