[PATCH v3 00/20] driver core: count references of the platform device's fwnode, not OF node

[PATCH v3 00/20] driver core: count references of the platform device's fwnode, not OF node

[Bartosz Golaszewski]

Platform device core provides helper interfaces for dealing with
dynamically created platform devices. Most users should use
platform_device_register_full() which encapsulates most of the
operations but some modules will want to use the split approach of
calling platform_device_alloc() + platform_device_add() separately for
various reasons.

With many platform devices now using dynamic software nodes as their
primary firmware nodes and with the platform device interface being
extended to also better cover the use-cases of secondary software nodes,
I believe it makes sense to switch to counting the references of all
kinds of firmware nodes.

To that end, I identified all users of platform_device_alloc() that also
assign dev.of_node or dev.fwnode manually. I noticed five cases where
the references are not increased as they should (patches 1-5 fix these
users) and provided three new functions in platform_device.h that now
become the preferred interfaces for assigning firmware nodes to dynamic
platform devices (in line with platform_device_add_data(),
platform_device_add_resources(), etc.). The bulk of the patches in this
series are small driver conversions to port all users to going through
the new functions that now encapsulate the refcount logic. With that
done, the final patch seamlessly switches to counting the references of
all firmware node types.

This effort is prerequisite of removing platform_device_release_full()
and unifying the release path for dynamic platform devices using
unmanaged software nodes.

Merging strategy: The entire series should go through the driver core
tree, possibly with an immutable branch provided to solve any potential
conflicts though these are rather unlikely.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
---
Changes in v3:
- Use device_set_node() where applicable
- Use __free(device_node) in fsl iommu driver
- Don't use __free() where not really required
- Add a patch updating the kerneldoc for platform_device_alloc()
- Collect more tags
- Link to v2: https://patch.msgid.link/20260629-pdev-fwnode-ref-v2-0-8abe2513f96e@oss.qualcomm.com

Changes in v2:
- Rebased on top of v7.2-rc1, dropped applied patches, collected tags
- Link to v1: https://patch.msgid.link/20260521-pdev-fwnode-ref-v1-0-88c324a1b8d2@oss.qualcomm.com

---
Bartosz Golaszewski (20):
      powerpc/powermac: fix OF node refcount
      driver core: platform: provide platform_device_set_of_node()
      driver core: platform: provide platform_device_set_fwnode()
      driver core: platform: provide platform_device_set_of_node_from_dev()
      driver core: update kerneldoc for platform_device_alloc()
      of: platform: use platform_device_set_of_node()
      powerpc/powermac: use platform_device_set_of_node()
      i2c: pxa-pci: use platform_device_set_of_node()
      iommu/fsl: use platform_device_set_of_node()
      net: bcmgenet: use platform_device_set_of_node()
      pmdomain: imx: use platform_device_set_of_node()
      mfd: tps6586: use platform_device_set_of_node()
      slimbus: qcom-ngd-ctrl: use platform_device_set_of_node()
      net: mv643xx: use platform_device_set_of_node()
      drm/xe/i2c: use platform_device_set_fwnode()
      platform/surface: gpe: use platform_device_set_fwnode()
      usb: chipidea: use platform_device_set_of_node_from_dev()
      usb: musb: use platform_device_set_of_node_from_dev()
      reset: rzg2l: use platform_device_set_of_node_from_dev()
      driver core: platform: count references to all kinds of firmware nodes

 arch/powerpc/platforms/powermac/low_i2c.c    |  2 +-
 drivers/base/platform.c                      | 61 ++++++++++++++++++++++++++--
 drivers/gpu/drm/xe/xe_i2c.c                  |  2 +-
 drivers/i2c/busses/i2c-pxa-pci.c             |  3 +-
 drivers/iommu/fsl_pamu.c                     | 16 +++-----
 drivers/mfd/tps6586x.c                       |  2 +-
 drivers/net/ethernet/broadcom/genet/bcmmii.c |  3 +-
 drivers/net/ethernet/marvell/mv643xx_eth.c   |  2 +-
 drivers/of/platform.c                        |  2 +-
 drivers/platform/surface/surface_gpe.c       |  2 +-
 drivers/pmdomain/imx/gpc.c                   |  3 +-
 drivers/reset/reset-rzg2l-usbphy-ctrl.c      |  2 +-
 drivers/slimbus/qcom-ngd-ctrl.c              |  2 +-
 drivers/usb/chipidea/core.c                  |  2 +-
 drivers/usb/musb/jz4740.c                    |  2 +-
 include/linux/platform_device.h              |  9 ++++
 16 files changed, 88 insertions(+), 27 deletions(-)
---
base-commit: 8cdeaa50eae8dad34885515f62559ee83e7e8dda
change-id: 20260520-pdev-fwnode-ref-d867836971eb

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

[PATCH v3 01/20] powerpc/powermac: fix OF node refcount

[Bartosz Golaszewski]

Platform devices created with platform_device_alloc() call
platform_device_release() when the last reference to the device's
kobject is dropped. This function calls of_node_put() unconditionally.
This works fine for devices created with platform_device_register_full()
but users of the split approach (platform_device_alloc() +
platform_device_add()) must bump the reference of the of_node they
assign manually. Add the missing call to of_node_get().

Cc: stable@vger.kernel.org
Fixes: 81e5d8646ff6 ("i2c/powermac: Register i2c devices from device-tree")
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
---
 arch/powerpc/platforms/powermac/low_i2c.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/powermac/low_i2c.c b/arch/powerpc/platforms/powermac/low_i2c.c
index da72a30ab8657e6dc7e6f3437af612155783d8f9..973f58771d9636605ed5d3e91b45008543b584d3 100644
--- a/arch/powerpc/platforms/powermac/low_i2c.c
+++ b/arch/powerpc/platforms/powermac/low_i2c.c
@@ -1471,7 +1471,7 @@ static int __init pmac_i2c_create_platform_devices(void)
 		if (bus->platform_dev == NULL)
 			return -ENOMEM;
 		bus->platform_dev->dev.platform_data = bus;
-		bus->platform_dev->dev.of_node = bus->busnode;
+		bus->platform_dev->dev.of_node = of_node_get(bus->busnode);
 		platform_device_add(bus->platform_dev);
 	}
 

-- 
2.47.3

Re: [PATCH v3 00/20] driver core: count references of the platform device's fwnode, not OF node

[Greg Kroah-Hartman]

On Mon, Jul 06, 2026 at 02:44:12PM +0200, Bartosz Golaszewski wrote:
> Platform device core provides helper interfaces for dealing with
> dynamically created platform devices. Most users should use
> platform_device_register_full() which encapsulates most of the
> operations but some modules will want to use the split approach of
> calling platform_device_alloc() + platform_device_add() separately for
> various reasons.
> 
> With many platform devices now using dynamic software nodes as their
> primary firmware nodes and with the platform device interface being
> extended to also better cover the use-cases of secondary software nodes,
> I believe it makes sense to switch to counting the references of all
> kinds of firmware nodes.
> 
> To that end, I identified all users of platform_device_alloc() that also
> assign dev.of_node or dev.fwnode manually. I noticed five cases where
> the references are not increased as they should (patches 1-5 fix these
> users) and provided three new functions in platform_device.h that now
> become the preferred interfaces for assigning firmware nodes to dynamic
> platform devices (in line with platform_device_add_data(),
> platform_device_add_resources(), etc.). The bulk of the patches in this
> series are small driver conversions to port all users to going through
> the new functions that now encapsulate the refcount logic. With that
> done, the final patch seamlessly switches to counting the references of
> all firmware node types.
> 
> This effort is prerequisite of removing platform_device_release_full()
> and unifying the release path for dynamic platform devices using
> unmanaged software nodes.
> 
> Merging strategy: The entire series should go through the driver core
> tree, possibly with an immutable branch provided to solve any potential
> conflicts though these are rather unlikely.

I've added this to the driver-core-testing branch now, thanks!

greg k-h