[PATCH] media: i2c: cvs: Register subdev nodes upon binding remote sensor

[PATCH] media: i2c: cvs: Register subdev nodes upon binding remote sensor

[Mauro Marinoni]

The Intel CVS driver acts as an intermediate CSI-2 bridge between
the host receiver (e.g. IPU7 ISYS) and the downstream camera sensor.
When the host driver initializes, its async notifier completes upon
binding the CVS bridge and registers its initial subdev nodes.

However, when the CVS bridge subsequently binds the downstream sensor
via its own async notifier callback (cvs_csi_notify_bound), it creates
the media pad link but omits calling v4l2_device_register_subdev_nodes().
As a consequence, downstream sensors declaring the flag
V4L2_SUBDEV_FL_HAS_DEVNODE (such as ov02c10) never have their
/dev/v4l-subdev* character device created, preventing userspace
frameworks like libcamera from opening the sensor.

Call v4l2_device_register_subdev_nodes() in cvs_csi_notify_bound() once
the media pad link is established to expose newly bound subdevices.

Signed-off-by: Mauro Nino Marinoni <mauro.marinoni@santannapisa.it>
---
 drivers/media/i2c/cvs/v4l2.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/media/i2c/cvs/v4l2.c b/drivers/media/i2c/cvs/v4l2.c
index 9fadca7a3bee..6ac4ad6d871c 100644
--- a/drivers/media/i2c/cvs/v4l2.c
+++ b/drivers/media/i2c/cvs/v4l2.c
@@ -13,6 +13,7 @@
 #include <media/v4l2-async.h>
 #include <media/v4l2-common.h>
 #include <media/v4l2-ctrls.h>
+#include <media/v4l2-device.h>
 #include <media/v4l2-event.h>
 #include <media/v4l2-fwnode.h>
 #include <media/v4l2-mc.h>
@@ -401,6 +402,7 @@ static int cvs_csi_notify_bound(struct v4l2_async_notifier *notifier,
 {
         struct icvs *ctx = notifier_to_csi(notifier);
         int pad;
+       int ret;
 
         pad = media_entity_get_fwnode_pad(&sd->entity, asc->match.fwnode,
                                           MEDIA_PAD_FL_SOURCE);
@@ -409,9 +411,16 @@ static int cvs_csi_notify_bound(struct v4l2_async_notifier *notifier,
 
         ctx->remote = &sd->entity.pads[pad];
 
-       return media_create_pad_link(&sd->entity, pad, &ctx->subdev.entity,
-                                    ICVS_CSI_PAD_SINK, MEDIA_LNK_FL_ENABLED |
-                                    MEDIA_LNK_FL_IMMUTABLE);
+       ret = media_create_pad_link(&sd->entity, pad, &ctx->subdev.entity,
+                                   ICVS_CSI_PAD_SINK, MEDIA_LNK_FL_ENABLED |
+                                   MEDIA_LNK_FL_IMMUTABLE);
+       if (ret)
+               return ret;
+
+       if (ctx->subdev.v4l2_dev)
+               return v4l2_device_register_subdev_nodes(ctx->subdev.v4l2_dev);
+
+       return 0;
 }
 
 /**
--
2.53.0

Re: [PATCH] media: i2c: cvs: Register subdev nodes upon binding remote sensor

[sakari.ailus]

Hi Mauro,

On Wed, Sep 30, 2026 at 11:28:08AM +0000, Mauro Marinoni wrote:
> The Intel CVS driver acts as an intermediate CSI-2 bridge between
> the host receiver (e.g. IPU7 ISYS) and the downstream camera sensor.
> When the host driver initializes, its async notifier completes upon
> binding the CVS bridge and registers its initial subdev nodes.
> 
> However, when the CVS bridge subsequently binds the downstream sensor
> via its own async notifier callback (cvs_csi_notify_bound), it creates
> the media pad link but omits calling v4l2_device_register_subdev_nodes().
> As a consequence, downstream sensors declaring the flag
> V4L2_SUBDEV_FL_HAS_DEVNODE (such as ov02c10) never have their
> /dev/v4l-subdev* character device created, preventing userspace
> frameworks like libcamera from opening the sensor.
> 
> Call v4l2_device_register_subdev_nodes() in cvs_csi_notify_bound() once
> the media pad link is established to expose newly bound subdevices.
> 
> Signed-off-by: Mauro Nino Marinoni <mauro.marinoni@santannapisa.it>

Please post patches against the media committers tree next branch or
linux-next master. This issue has been fixed by commit
7456b40bc992a3fc34b587545716729923d507b9 .

-- 
Regards,

Sakari Ailus

R: [PATCH] media: i2c: cvs: Register subdev nodes upon binding remote sensor

[Mauro Marinoni]

Thanks for the pointer! 
I was testing on v7.3-rc5 and missed that commit in media-committers/next. 
I can confirm that commit 7456b40bc992 properly addresses the missing subdev node registration. I've tested on an XPS13 9350.

Sorry for the noise, and thanks again for the review.

Best regards,
Mauro

________________________________________
Da: sakari.ailus@linux.intel.com <sakari.ailus@linux.intel.com>
Inviato: mercoledì 30 settembre 2026 13:59
A: Mauro Marinoni
Cc: miguel.vadillo@intel.com; mchehab@kernel.org; linux-media@vger.kernel.org; linux-kernel@vger.kernel.org
Oggetto: Re: [PATCH] media: i2c: cvs: Register subdev nodes upon binding remote sensor

Hi Mauro,

On Wed, Sep 30, 2026 at 11:28:08AM +0000, Mauro Marinoni wrote:
> The Intel CVS driver acts as an intermediate CSI-2 bridge between
> the host receiver (e.g. IPU7 ISYS) and the downstream camera sensor.
> When the host driver initializes, its async notifier completes upon
> binding the CVS bridge and registers its initial subdev nodes.
>
> However, when the CVS bridge subsequently binds the downstream sensor
> via its own async notifier callback (cvs_csi_notify_bound), it creates
> the media pad link but omits calling v4l2_device_register_subdev_nodes().
> As a consequence, downstream sensors declaring the flag
> V4L2_SUBDEV_FL_HAS_DEVNODE (such as ov02c10) never have their
> /dev/v4l-subdev* character device created, preventing userspace
> frameworks like libcamera from opening the sensor.
>
> Call v4l2_device_register_subdev_nodes() in cvs_csi_notify_bound() once
> the media pad link is established to expose newly bound subdevices.
>
> Signed-off-by: Mauro Nino Marinoni <mauro.marinoni@santannapisa.it>

Please post patches against the media committers tree next branch or
linux-next master. This issue has been fixed by commit
7456b40bc992a3fc34b587545716729923d507b9 .

--
Regards,

Sakari Ailus

[PATCH] media: i2c: cvs: Register subdev nodes upon binding remote sensor

[Mauro Marinoni]

The Intel CVS driver acts as an intermediate CSI-2 bridge between
the host receiver (e.g. IPU7 ISYS) and the downstream camera sensor.
When the host driver initializes, its async notifier completes upon
binding the CVS bridge and registers its initial subdev nodes.

However, when the CVS bridge subsequently binds the downstream sensor
via its own async notifier callback (cvs_csi_notify_bound), it creates
the media pad link but omits calling v4l2_device_register_subdev_nodes().
As a consequence, downstream sensors declaring the flag
V4L2_SUBDEV_FL_HAS_DEVNODE (such as ov02c10) never have their
/dev/v4l-subdev* character device created, preventing userspace
frameworks like libcamera from opening the sensor.

Call v4l2_device_register_subdev_nodes() in cvs_csi_notify_bound() once
the media pad link is established to expose newly bound subdevices.

Signed-off-by: Mauro Nino Marinoni <mauro.marinoni@santannapisa.it>
---
 drivers/media/i2c/cvs/v4l2.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/media/i2c/cvs/v4l2.c b/drivers/media/i2c/cvs/v4l2.c
index 9fadca7a3bee..6ac4ad6d871c 100644
--- a/drivers/media/i2c/cvs/v4l2.c
+++ b/drivers/media/i2c/cvs/v4l2.c
@@ -13,6 +13,7 @@
 #include <media/v4l2-async.h>
 #include <media/v4l2-common.h>
 #include <media/v4l2-ctrls.h>
+#include <media/v4l2-device.h>
 #include <media/v4l2-event.h>
 #include <media/v4l2-fwnode.h>
 #include <media/v4l2-mc.h>
@@ -401,6 +402,7 @@ static int cvs_csi_notify_bound(struct v4l2_async_notifier *notifier,
 {
         struct icvs *ctx = notifier_to_csi(notifier);
         int pad;
+       int ret;
 
         pad = media_entity_get_fwnode_pad(&sd->entity, asc->match.fwnode,
                                           MEDIA_PAD_FL_SOURCE);
@@ -409,9 +411,16 @@ static int cvs_csi_notify_bound(struct v4l2_async_notifier *notifier,
 
         ctx->remote = &sd->entity.pads[pad];
 
-       return media_create_pad_link(&sd->entity, pad, &ctx->subdev.entity,
-                                    ICVS_CSI_PAD_SINK, MEDIA_LNK_FL_ENABLED |
-                                    MEDIA_LNK_FL_IMMUTABLE);
+       ret = media_create_pad_link(&sd->entity, pad, &ctx->subdev.entity,
+                                   ICVS_CSI_PAD_SINK, MEDIA_LNK_FL_ENABLED |
+                                   MEDIA_LNK_FL_IMMUTABLE);
+       if (ret)
+               return ret;
+
+       if (ctx->subdev.v4l2_dev)
+               return v4l2_device_register_subdev_nodes(ctx->subdev.v4l2_dev);
+
+       return 0;
 }
 
 /**
--
2.53.0