[PATCH] media: ivsc: csi: Add sensor node in bound callback

[PATCH] media: ivsc: csi: Add sensor node in bound callback

[Arpith Alexander]

The IPU6 ISYS creates sub-device nodes in its bound and complete
callbacks. A sensor behind the IVSC is bound by the IVSC's own notifier,
after the ISYS's bound callback has already run for the IVSC, and
mei_csi_notify_bound() doesn't create a node. Unless another device
binds to the ISYS afterwards, the sensor's node is therefore only
created by the ISYS's complete callback, which runs once every sensor in
the graph is bound.

Commit 4fdb0342f05e ("media: ipu-bridge: Add Himax HM1092 IR sensor") added
the HM1092 to the ipu-bridge list. The HM1092 has no driver in mainline
yet, so it never binds and the complete callback never runs. The OV02C10
behind the IVSC therefore never gets a sub-device node.

On a Dell XPS 13 9340, libcamera then fails with:

'ov02c10 3-0036': Failed to open V4L2 device '': No such file or directory
No valid pipeline for sensor 'ov02c10 3-0036', skipping

Register the sub-device nodes in mei_csi_notify_bound() as well, so that
the sensor's node is created as soon as it binds. If the complete callback
runs later, v4l2_device_register_subdev_nodes() skips sub-devices that
already have a node.

Commit 7456b40bc992 ("media: i2c: cvs: Add sensor node in bound callback")
is the CVS equivalent of this IVSC fix.

Fixes: 29006e196a56 ("media: pci: intel: ivsc: Add CSI submodule")
Cc: stable@vger.kernel.org
Signed-off-by: Arpith Alexander <arpith99@gmail.com>
---
Tested on a Dell XPS 13 9340 (Meteor Lake IPU6, OV02C10 behind the
IVSC) with v7.4-rc1. ipu-bridge connects both sensors ("Connected 2
cameras"), the HM1092 has no driver and doesn't bind, and the OV02C10
now gets its sub-device node. libcamera finds the camera and streams at
30 fps (cam -c 1 -C10). The camera last worked on v7.2.

The test kernel also had my two other v7.4-rc1 fixes for this laptop:
https://lore.kernel.org/linux-spi/20261103131435.21838-1-arpith99@gmail.com/
https://lore.kernel.org/linux-media/20261103163814.96980-1-arpith99@gmail.com/

Unlike a revert of commit 4fdb0342f05e, this keeps the HM1092 entry for
the pending driver, and it also covers kernels built without that driver
once it is merged.

 drivers/media/pci/intel/ivsc/mei_csi.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/media/pci/intel/ivsc/mei_csi.c b/drivers/media/pci/intel/ivsc/mei_csi.c
index 005b1414a252..f9513cffaacd 100644
--- a/drivers/media/pci/intel/ivsc/mei_csi.c
+++ b/drivers/media/pci/intel/ivsc/mei_csi.c
@@ -29,6 +29,7 @@
 #include <media/ipu-bridge.h>
 #include <media/v4l2-async.h>
 #include <media/v4l2-ctrls.h>
+#include <media/v4l2-device.h>
 #include <media/v4l2-fwnode.h>
 #include <media/v4l2-subdev.h>
 
@@ -513,7 +514,7 @@ static int mei_csi_notify_bound(struct v4l2_async_notifier *notifier,
 				struct v4l2_async_connection *asd)
 {
 	struct mei_csi *csi = notifier_to_csi(notifier);
-	int pad;
+	int pad, ret;
 
 	pad = media_entity_get_fwnode_pad(&subdev->entity, asd->match.fwnode,
 					  MEDIA_PAD_FL_SOURCE);
@@ -522,10 +523,14 @@ static int mei_csi_notify_bound(struct v4l2_async_notifier *notifier,
 
 	csi->remote = &subdev->entity.pads[pad];
 
-	return media_create_pad_link(&subdev->entity, pad,
-				     &csi->subdev.entity, CSI_PAD_SINK,
-				     MEDIA_LNK_FL_ENABLED |
-				     MEDIA_LNK_FL_IMMUTABLE);
+	ret = media_create_pad_link(&subdev->entity, pad,
+				    &csi->subdev.entity, CSI_PAD_SINK,
+				    MEDIA_LNK_FL_ENABLED |
+				    MEDIA_LNK_FL_IMMUTABLE);
+	if (ret)
+		return ret;
+
+	return v4l2_device_register_subdev_nodes(subdev->v4l2_dev);
 }
 
 static void mei_csi_notify_unbind(struct v4l2_async_notifier *notifier,

base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4
-- 
2.55.0

Re: [PATCH] media: ivsc: csi: Add sensor node in bound callback

[Sergey Zagursky]

Hi Arpith,

Same regression on a Dell XPS 16 9640 (BIOS 1.4.1, OV02C10 behind the
IVSC, HIMX1092:00 in ACPI). I reported it before finding your patch:
https://lore.kernel.org/r/20261109142140.ov02c10-hm1092-regression.e938253b8516@gmail.com/

I tested the same change (identical apart from the declaration of ret)
on CachyOS 7.2.8, with modules built from kernel.org v7.2.8 sources:
- 7.2.8 plus only the HM1092 entry from 4fdb0342f05e: no sub-device
  node for the OV02C10, libcamera skips the sensor.
- Same plus this change: the node is created, libcamera and PipeWire
  find the camera, and "cam -c1 --capture=10" streams at 30 fps.
- This change without the HM1092 entry, so .complete() runs after the
  node already exists: still one node for the sensor, streams fine.
No kernel warnings in any of these.

Tested-by: Sergey Zagursky <gvozdoder@gmail.com>

Sakari, if you pick this up, could you also add
Closes: https://lore.kernel.org/r/20261109142140.ov02c10-hm1092-regression.e938253b8516@gmail.com/

I used an AI assistant (Claude) to analyse the problem; the tests
above ran on my machine.

Thanks,
Sergey