Hello,

This implements what was agreed in the "ipu-bridge: software nodes are
never unregistered" thread [1]: the software nodes are deliberately
leaked and cannot be removed (circular remote-endpoint references), so
instead of a teardown, make the two halves of the intended design work -
the nodes must actually survive module unload, and a rebind must reuse
them instead of failing.

[1/2] makes the registered properties self-contained in the never-freed
bridge allocation. One correction to my original report: the property
name strings I pointed at (prop_names) were never a problem - struct
ipu_property_names holds char arrays, so those are already copied. The
real module-image references were the "link-frequencies" property
values (pointing into the ipu_supported_sensors[] rodata) and the
"lens-focus" property name string literal. The link-frequencies one is
directly observable on hardware: with the creator module unloaded, a
re-probing sensor reads poisoned frequencies ("supported link freq
419200000ll not found"); reloading the module - which puts identical
rodata back at the same address - makes the same probe succeed again.

[2/2] adds the reuse path to ipu_bridge_init(): if the IPU HID node is
already registered, point the IPU's secondary fwnode at it and return.
The sensors' ACPI fwnodes keep their secondary pointers from the first
bind (nothing clears them), and with [1/2] the nodes they point at are
still valid.

Tested on a Surface Pro 7+ (IPU6 Tiger Lake, OV5693 + OV8865 + OV7251):
the PCI remove -> module unload -> rescan -> modprobe sequence from the
report, which today is fatal until reboot (-EEXIST), completes cleanly
with this series - "Reusing the previously registered software nodes" -
twice in a row, with all three cameras streaming after each rebind. Also
re-verified per Sakari's question that the failure is identical when all
sensor sub-device drivers are unbound before the PCI remove (answered
with the data in [1]).

The series was developed with the assistance of an AI tool (Claude) and
verified on the hardware described above.

Thanks,
D. Manresa

D. Manresa (2):
  media: ipu-bridge: don't reference the module image from the software
    nodes
  media: ipu-bridge: reuse the software nodes on rebind

 drivers/media/pci/intel/ipu-bridge.c | 38 ++++++++++++++++++++++++++---
 include/media/ipu-bridge.h           |  9 +++++++++
 2 files changed, 44 insertions(+), 3 deletions(-)

--
2.43.0

Hello,

v2 of the ipu-bridge rebind series, addressing Sakari's review of v2/2:

- shortened the 2/2 commit message (dropped the cross-reference to 1/2
  and the IVSC/VCM elaboration);
- dev_info() -> dev_dbg() on the reuse path;
- replaced the free-text AI note with the Assisted-by: tag per
  Documentation/process/coding-assistants.rst, in both patches.

No code changes other than the log level. The v1 testing stands: on a
Surface Pro 7+ (IPU6, OV5693 + OV8865 + OV7251) the PCI remove ->
module unload -> rescan -> modprobe sequence, fatal today (-EEXIST),
completes cleanly with the series - twice in a row - with all three
cameras streaming after each rebind. (The same sequence with all sensor
sub-device drivers unbound first fails identically without the series,
as reported in the parent thread.)

Thanks,
D. Manresa

D. Manresa (2):
  media: ipu-bridge: don't reference the module image from software
    nodes
  media: ipu-bridge: reuse the software nodes on rebind

 drivers/media/pci/intel/ipu-bridge.c | 38 ++++++++++++++++++++++++++---
 include/media/ipu-bridge.h           |  9 +++++++++
 2 files changed, 44 insertions(+), 3 deletions(-)

--
2.43.0

The software nodes registered by ipu_bridge_init() are deliberately
never unregistered: sensor drivers and the fwnode graph keep references
to them, so they are left registered when the ipu-bridge module is
unloaded and a later rebind is intended to reuse the already registered
nodes.

For that to work, nothing reachable from the registered nodes may point
into the ipu-bridge module image. Most of the data already lives in the
dedicated, never freed, struct ipu_bridge allocation: the property name
strings in struct ipu_property_names are character arrays copied into
the per-sensor struct, the node name strings are likewise character
arrays inside the struct, and the data-lanes array is a struct
ipu_bridge member precisely so that "it survives if the module is
unloaded along with the rest of the struct".

Two references into the module image remain, though:

1. The values of the "link-frequencies" endpoint property point at
   cfg->link_freqs inside the const ipu_supported_sensors[] table in
   module rodata.

2. The name of the "lens-focus" device property is a string literal in
   module rodata.

Both dangle as soon as the module is unloaded, while the properties
that carry them stay registered and readable. In practice, after
unloading and reloading the IPU modules on a Surface Pro 7+ (IPU6,
ov8865 + ov5693 + ov7251), re-probing sensor drivers read poisoned
link-frequencies from the surviving nodes and fail to probe:

  ov8865: failed to find 360000000 clk rate in endpoint link-frequencies
  ov5693: supported link freq 419200000 not found

where 419200000/360000000 are exactly the values the bridge had
originally published for those sensors, i.e. the properties no longer
return their original contents. Depending on what happens to the freed
module mapping, reading the properties can also fault. Similarly, a VCM
lookup through the "lens-focus" reference can no longer match (or
faults) once the property's name pointer is dangling.

Copy the link frequencies and the "lens-focus" property name into
struct ipu_bridge, next to the data-lanes array kept there for the same
reason, and make the registered properties point at those copies, so
the nodes survive module unload intact. These were the only remaining
references from the registered nodes into the module image (the
sensor->vcm_type pointer into ipu_vcm_types[] is only dereferenced
during ipu_bridge_init() itself and is not reachable from the nodes).

Assisted-by: LLM

Fixes: 803abec64ef9 ("media: ipu3-cio2: Add cio2-bridge to ipu3-cio2 driver")
Fixes: 68b9bcc8a534 ("media: ipu3-cio2: Add support for instantiating i2c-clients for VCMs")
Signed-off-by: D. Manresa <dmanresa@gmail.com>
---
 drivers/media/pci/intel/ipu-bridge.c | 14 +++++++++++---
 include/media/ipu-bridge.h           |  9 +++++++++
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/drivers/media/pci/intel/ipu-bridge.c b/drivers/media/pci/intel/ipu-bridge.c
index 1bb3a3e..4de42ed 100644
--- a/drivers/media/pci/intel/ipu-bridge.c
+++ b/drivers/media/pci/intel/ipu-bridge.c
@@ -503,7 +503,8 @@ static void ipu_bridge_create_fwnode_properties(
 		sensor->vcm_ref[0] =
 			SOFTWARE_NODE_REFERENCE(&sensor->swnodes[SWNODE_VCM]);
 		sensor->dev_properties[3] =
-			PROPERTY_ENTRY_REF_ARRAY("lens-focus", sensor->vcm_ref);
+			PROPERTY_ENTRY_REF_ARRAY(bridge->lens_focus,
+						 sensor->vcm_ref);
 	}
 
 	sensor->ep_properties[0] = PROPERTY_ENTRY_U32(
@@ -516,11 +517,17 @@ static void ipu_bridge_create_fwnode_properties(
 					sensor->prop_names.remote_endpoint,
 					sensor->local_ref);
 
-	if (cfg->nr_link_freqs > 0)
+	if (cfg->nr_link_freqs > 0) {
+		u64 *link_freqs = bridge->link_freqs[sensor - bridge->sensors];
+
+		memcpy(link_freqs, cfg->link_freqs,
+		       cfg->nr_link_freqs * sizeof(*link_freqs));
+
 		sensor->ep_properties[3] = PROPERTY_ENTRY_U64_ARRAY_LEN(
 			sensor->prop_names.link_frequencies,
-			cfg->link_freqs,
+			link_freqs,
 			cfg->nr_link_freqs);
+	}
 
 	sensor->ipu_properties[0] = PROPERTY_ENTRY_U32_ARRAY_LEN(
 					sensor->prop_names.data_lanes,
@@ -943,6 +950,7 @@ int ipu_bridge_init(struct device *dev,
 
 	strscpy(bridge->ipu_node_name, IPU_HID,
 		sizeof(bridge->ipu_node_name));
+	strscpy(bridge->lens_focus, "lens-focus", sizeof(bridge->lens_focus));
 	bridge->ipu_hid_node.name = bridge->ipu_node_name;
 	bridge->dev = dev;
 	bridge->parse_sensor_fwnode = parse_sensor_fwnode;
diff --git a/include/media/ipu-bridge.h b/include/media/ipu-bridge.h
index 16fac76..4e91ec3 100644
--- a/include/media/ipu-bridge.h
+++ b/include/media/ipu-bridge.h
@@ -164,6 +164,15 @@ struct ipu_bridge {
 	char ipu_node_name[ACPI_ID_LEN];
 	struct software_node ipu_hid_node;
 	u32 data_lanes[4];
+	/*
+	 * The software nodes registered by the bridge are deliberately never
+	 * unregistered (see ipu_bridge_init()), so every string and array
+	 * they reference must live in this never freed struct rather than in
+	 * the module image, so that the nodes stay intact if the module is
+	 * unloaded.
+	 */
+	char lens_focus[sizeof("lens-focus")];
+	u64 link_freqs[IPU_MAX_PORTS][MAX_NUM_LINK_FREQS];
 	unsigned int n_sensors;
 	struct ipu_sensor sensors[IPU_MAX_PORTS];
 };
-- 
2.43.0

The software nodes registered by ipu_bridge_init() are deliberately
never unregistered, and the intended design is for a rebind to reuse
the already registered nodes. That reuse path however only exists for
the case where the IPU device kept its secondary fwnode link, which the
fwnode graph check at the top of ipu_bridge_init() detects: then the
function returns early. When the link is gone, ipu_bridge_init()
unconditionally registers the IPU HID software node again, which fails
with -EEXIST on the sysfs name (the node from the previous bind is
still registered) and the IPU driver fails to probe.

That is exactly what happens when the IPU PCI device is removed and
re-scanned: device_del() unsets the ACPI companion, and
set_primary_fwnode(dev, NULL) then clears the ACPI fwnode's ->secondary
pointer, so the fwnode graph check on the next probe finds no endpoints
and falls through to registration. Observed on a Surface Pro 7+ (IPU6):

  echo 1 > /sys/bus/pci/devices/0000:00:05.0/remove
  modprobe -r intel_ipu6_isys intel_ipu6   # ipu-bridge unloads too
  echo 1 > /sys/bus/pci/rescan
  modprobe intel_ipu6

  sysfs: cannot create duplicate filename '/kernel/software_nodes/INT343E'
  intel-ipu6 0000:00:05.0: Failed to register the IPU HID node
  intel-ipu6: probe of 0000:00:05.0 failed with error -17

after which the cameras are unusable until reboot.

Add the missing reuse path: if the IPU software node is already
registered, look it up with software_node_find_by_name(), point the
device's secondary fwnode at it and return success. That is all a
rebind needs: the sensor, IVSC and VCM links live on devices that
survive an IPU unbind, so nothing has cleared those.

software_node_find_by_name() takes a reference on the node it returns;
drop it right away since the node is kept alive by its never dropped
registration.

Assisted-by: LLM

Fixes: 803abec64ef9 ("media: ipu3-cio2: Add cio2-bridge to ipu3-cio2 driver")
Signed-off-by: D. Manresa <dmanresa@gmail.com>
---
 drivers/media/pci/intel/ipu-bridge.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/media/pci/intel/ipu-bridge.c b/drivers/media/pci/intel/ipu-bridge.c
index 4de42ed..6fa1c3c 100644
--- a/drivers/media/pci/intel/ipu-bridge.c
+++ b/drivers/media/pci/intel/ipu-bridge.c
@@ -930,6 +930,7 @@ static DEFINE_MUTEX(ipu_bridge_mutex);
 int ipu_bridge_init(struct device *dev,
 		    ipu_parse_sensor_fwnode_t parse_sensor_fwnode)
 {
+	const struct software_node *ipu_node;
 	struct fwnode_handle *fwnode;
 	struct ipu_bridge *bridge;
 	unsigned int i;
@@ -940,6 +941,29 @@ int ipu_bridge_init(struct device *dev,
 	if (!ipu_bridge_check_fwnode_graph(dev_fwnode(dev)))
 		return 0;
 
+	/*
+	 * The software nodes registered by a previous ipu_bridge_init() call
+	 * are deliberately kept registered when the module is unloaded, and
+	 * the sensors' ACPI fwnodes still have them as their secondary
+	 * fwnodes. If the IPU software node is already registered this is a
+	 * rebind, e.g. after the PCI device was removed and re-scanned,
+	 * which drops the IPU's secondary fwnode link. Registering the nodes
+	 * again would fail with -EEXIST, so instead reuse them and just
+	 * restore the IPU's secondary fwnode link.
+	 */
+	ipu_node = software_node_find_by_name(NULL, IPU_HID);
+	if (ipu_node) {
+		fwnode = software_node_fwnode(ipu_node);
+		set_secondary_fwnode(dev, fwnode);
+		/*
+		 * The node stays registered, it does not need the reference
+		 * software_node_find_by_name() took to stay alive.
+		 */
+		fwnode_handle_put(fwnode);
+		dev_dbg(dev, "Reusing the previously registered software nodes\n");
+		return 0;
+	}
+
 	if (!ipu_bridge_ivsc_is_ready())
 		return dev_err_probe(dev, -EPROBE_DEFER,
 				     "waiting for IVSC to become ready\n");
-- 
2.43.0

Hi D.,

On Mon, Aug 31, 2026 at 04:03:03PM +0200, D. Manresa wrote:
> The software nodes registered by ipu_bridge_init() are deliberately
> never unregistered, and the intended design is for a rebind to reuse
> the already registered nodes. That reuse path however only exists for
> the case where the IPU device kept its secondary fwnode link, which the
> fwnode graph check at the top of ipu_bridge_init() detects: then the
> function returns early. When the link is gone, ipu_bridge_init()
> unconditionally registers the IPU HID software node again, which fails
> with -EEXIST on the sysfs name (the node from the previous bind is
> still registered) and the IPU driver fails to probe.
> 
> That is exactly what happens when the IPU PCI device is removed and
> re-scanned: device_del() unsets the ACPI companion, and
> set_primary_fwnode(dev, NULL) then clears the ACPI fwnode's ->secondary
> pointer, so the fwnode graph check on the next probe finds no endpoints
> and falls through to registration. Observed on a Surface Pro 7+ (IPU6):
> 
>   echo 1 > /sys/bus/pci/devices/0000:00:05.0/remove
>   modprobe -r intel_ipu6_isys intel_ipu6   # ipu-bridge unloads too
>   echo 1 > /sys/bus/pci/rescan
>   modprobe intel_ipu6
> 
>   sysfs: cannot create duplicate filename '/kernel/software_nodes/INT343E'
>   intel-ipu6 0000:00:05.0: Failed to register the IPU HID node
>   intel-ipu6: probe of 0000:00:05.0 failed with error -17
> 
> after which the cameras are unusable until reboot.
> 
> Add the missing reuse path: if the IPU software node is already
> registered, look it up with software_node_find_by_name(), point the
> device's secondary fwnode at it and return success. That is all a
> rebind needs: the sensor, IVSC and VCM links live on devices that
> survive an IPU unbind, so nothing has cleared those.
> 
> software_node_find_by_name() takes a reference on the node it returns;
> drop it right away since the node is kept alive by its never dropped
> registration.
> 
> Assisted-by: LLM

Which one?

There's also an extra newline here. (No need to resend if you just provide
the info.)

> 
> Fixes: 803abec64ef9 ("media: ipu3-cio2: Add cio2-bridge to ipu3-cio2 driver")
> Signed-off-by: D. Manresa <dmanresa@gmail.com>
> ---
>  drivers/media/pci/intel/ipu-bridge.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/drivers/media/pci/intel/ipu-bridge.c b/drivers/media/pci/intel/ipu-bridge.c
> index 4de42ed..6fa1c3c 100644
> --- a/drivers/media/pci/intel/ipu-bridge.c
> +++ b/drivers/media/pci/intel/ipu-bridge.c
> @@ -930,6 +930,7 @@ static DEFINE_MUTEX(ipu_bridge_mutex);
>  int ipu_bridge_init(struct device *dev,
>  		    ipu_parse_sensor_fwnode_t parse_sensor_fwnode)
>  {
> +	const struct software_node *ipu_node;
>  	struct fwnode_handle *fwnode;
>  	struct ipu_bridge *bridge;
>  	unsigned int i;
> @@ -940,6 +941,29 @@ int ipu_bridge_init(struct device *dev,
>  	if (!ipu_bridge_check_fwnode_graph(dev_fwnode(dev)))
>  		return 0;
>  
> +	/*
> +	 * The software nodes registered by a previous ipu_bridge_init() call
> +	 * are deliberately kept registered when the module is unloaded, and
> +	 * the sensors' ACPI fwnodes still have them as their secondary
> +	 * fwnodes. If the IPU software node is already registered this is a
> +	 * rebind, e.g. after the PCI device was removed and re-scanned,
> +	 * which drops the IPU's secondary fwnode link. Registering the nodes
> +	 * again would fail with -EEXIST, so instead reuse them and just
> +	 * restore the IPU's secondary fwnode link.
> +	 */
> +	ipu_node = software_node_find_by_name(NULL, IPU_HID);
> +	if (ipu_node) {
> +		fwnode = software_node_fwnode(ipu_node);
> +		set_secondary_fwnode(dev, fwnode);
> +		/*
> +		 * The node stays registered, it does not need the reference
> +		 * software_node_find_by_name() took to stay alive.
> +		 */
> +		fwnode_handle_put(fwnode);
> +		dev_dbg(dev, "Reusing the previously registered software nodes\n");
> +		return 0;
> +	}
> +
>  	if (!ipu_bridge_ivsc_is_ready())
>  		return dev_err_probe(dev, -EPROBE_DEFER,
>  				     "waiting for IVSC to become ready\n");

-- 
Regards,

Sakari Ailus

On Mon, 1 Sep 2026, Sakari Ailus wrote:
> > Assisted-by: LLM
>
> Which one?

Anthropic Claude (model: Fable 5), for both patches in the series - it did
the code, the commit messages and the failure analysis, directed and
verified on hardware by me. So:

  Assisted-by: LLM (Anthropic Claude, Fable 5)

if that form works for you - coding-assistants.rst only shows the generic
"Assisted-by: LLM [tools]" shape, so happy to adjust to whatever spelling
you prefer.

> There's also an extra newline here. (No need to resend if you just provide
> the info.)

An editing artifact - the trailer block should be contiguous, no blank line
between Assisted-by and Fixes. If you can fix both up when applying, great;
otherwise say the word and I will send a v3 with the corrected trailers.

Thanks,
D. Manresa <dmanresa@gmail.com>