Hi all,

After merging the driver-core tree, today's linux-next build (powerpc
ppc64_defconfig) failed like this:

drivers/i2c/i2c-core-base.c: In function 'delete_device_store':
drivers/i2c/i2c-core-base.c:1350:58: error: passing argument 3 of 'device_find_child' from incompatible pointer type [-Wincompatible-pointer-types]
 1350 |         child_dev = device_find_child(&adap->dev, &addr, __i2c_find_user_addr);
      |                                                          ^~~~~~~~~~~~~~~~~~~~
      |                                                          |
      |                                                          int (*)(struct device *, void *)
In file included from include/linux/acpi.h:14,
                 from drivers/i2c/i2c-core-base.c:16:
include/linux/device.h:1085:49: note: expected 'device_match_t' {aka 'int (*)(struct device *, const void *)'} but argument is of type 'int (*)(struct device *, void *)'
 1085 |                                  device_match_t match);
      |                                  ~~~~~~~~~~~~~~~^~~~~

Caused by commit

  f1e8bf56320a ("driver core: Constify API device_find_child() and adapt for various usages")

interacting with commit

  3cfe39b3a845 ("i2c: Replace list-based mechanism for handling userspace-created clients")

from the i2c tree.

I have applied the following merge fix patch.

From: Stephen Rothwell <sfr@canb.auug.org.au>
Date: Mon, 6 Jan 2025 15:33:36 +1100
Subject: [PATCH] fix up for "driver core: Constify API device_find_child() and
 adapt for various usages"

interacting with commit

  3cfe39b3a845 ("i2c: Replace list-based mechanism for handling userspace-created clients")

from the i2c tree.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
---
 drivers/i2c/i2c-core-base.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index bd90a6084fc0..c21a16aa96dc 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1306,10 +1306,10 @@ new_device_store(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_WO(new_device);
 
-static int __i2c_find_user_addr(struct device *dev, void *addrp)
+static int __i2c_find_user_addr(struct device *dev, const void *addrp)
 {
 	struct i2c_client *client = i2c_verify_client(dev);
-	unsigned short addr = *(unsigned short *)addrp;
+	unsigned short addr = *(const unsigned short *)addrp;
 
 	return client && client->flags & I2C_CLIENT_USER &&
 	       i2c_encode_flags_to_addr(client) == addr;
-- 
2.45.2

-- 
Cheers,
Stephen Rothwell

On 1/6/2025 12:53 PM, Stephen Rothwell wrote:
> Hi all,
> 
> After merging the driver-core tree, today's linux-next build (powerpc
> ppc64_defconfig) failed like this:
> 
> drivers/i2c/i2c-core-base.c: In function 'delete_device_store':
> drivers/i2c/i2c-core-base.c:1350:58: error: passing argument 3 of 'device_find_child' from incompatible pointer type [-Wincompatible-pointer-types]
>  1350 |         child_dev = device_find_child(&adap->dev, &addr, __i2c_find_user_addr);
>       |                                                          ^~~~~~~~~~~~~~~~~~~~
>       |                                                          |
>       |                                                          int (*)(struct device *, void *)
> In file included from include/linux/acpi.h:14,
>                  from drivers/i2c/i2c-core-base.c:16:
> include/linux/device.h:1085:49: note: expected 'device_match_t' {aka 'int (*)(struct device *, const void *)'} but argument is of type 'int (*)(struct device *, void *)'
>  1085 |                                  device_match_t match);
>       |                                  ~~~~~~~~~~~~~~~^~~~~
> 
> Caused by commit
> 
>   f1e8bf56320a ("driver core: Constify API device_find_child() and adapt for various usages")
> 
> interacting with commit
> 
>   3cfe39b3a845 ("i2c: Replace list-based mechanism for handling userspace-created clients")
> 
> from the i2c tree.
> 
> I have applied the following merge fix patch.
> 
> From: Stephen Rothwell <sfr@canb.auug.org.au>
> Date: Mon, 6 Jan 2025 15:33:36 +1100
> Subject: [PATCH] fix up for "driver core: Constify API device_find_child() and
>  adapt for various usages"
> 
> interacting with commit
> 
>   3cfe39b3a845 ("i2c: Replace list-based mechanism for handling userspace-created clients")
> 
> from the i2c tree.
> 
> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
> ---
>  drivers/i2c/i2c-core-base.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index bd90a6084fc0..c21a16aa96dc 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -1306,10 +1306,10 @@ new_device_store(struct device *dev, struct device_attribute *attr,
>  }
>  static DEVICE_ATTR_WO(new_device);
>  
> -static int __i2c_find_user_addr(struct device *dev, void *addrp)
> +static int __i2c_find_user_addr(struct device *dev, const void *addrp)
>  {
>  	struct i2c_client *client = i2c_verify_client(dev);
> -	unsigned short addr = *(unsigned short *)addrp;
> +	unsigned short addr = *(const unsigned short *)addrp;
>  
>  	return client && client->flags & I2C_CLIENT_USER &&
>  	       i2c_encode_flags_to_addr(client) == addr;

LGTM, thank you Stephen for this fix.
Reviewed-by: Zijun Hu <quic_zijuhu@quicinc.com>