i3c: fix uninitialized variable use in i2c setup

From: Jamie Iles <[email protected]>

commit 6cbf8b38dfe3aabe330f2c356949bc4d6a1f034f upstream.

Commit 31b9887c7258 ("i3c: remove i2c board info from i2c_dev_desc") removed the boardinfo from i2c_dev_desc to decouple device enumeration from setup but did not correctly lookup the i2c_dev_desc to store the new device, instead dereferencing an uninitialized variable.

Lookup the device that has already been registered by address to store the i2c client device.

---
This fixes the previously reported -Wuninitialized that gets upgraded to an error on 5.15:

drivers/i3c/master.c:2203:3: error: variable 'i2cdev' is uninitialized when used here [-Werror,-Wuninitialized]

   2203 |                 i2cdev->dev = i2c_new_client_device(adap, &i2cboardinfo->base);
        |                 ^~~~~~

As my previous messages pointing out this fix for a simple cherry-pick were seemingly ignored, I sent the patch hoping it would get this issue finally resolved.

https://lore.kernel.org/20260318023542.GA2596820@ax162/
https://lore.kernel.org/20260413185112.GA501334@ax162/

---
 drivers/i3c/master.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

index dee694024f28..5df943d25cf0 100644
@@ -2199,8 +2199,13 @@ static int i3c_master_i2c_adapter_init(struct i3c_master_controller *master)
 	 * We silently ignore failures here. The bus should keep working
 	 * correctly even if one or more i2c devices are not registered.
 	 */
-	list_for_each_entry(i2cboardinfo, &master->boardinfo.i2c, node)
+	list_for_each_entry(i2cboardinfo, &master->boardinfo.i2c, node) {
+		i2cdev = i3c_master_find_i2c_dev_by_addr(master,
+							 i2cboardinfo->base.addr);
+		if (WARN_ON(!i2cdev))
+			continue;
 		i2cdev->dev = i2c_new_client_device(adap, &i2cboardinfo->base);
+	}
 
 	return 0;
 }

base-commit: b9d57c40a767db4d2ef905abb91f73cbe0a791e1

2.53.0