The of_device_unregister call in therm_windtunnel's module_exit procedure
does not fully reverse the effects of of_platform_device_create in the
module_init prodedure.  Once you unload this module, it is impossible
to load it ever again since only the first of_platform_device_create
call on the fan node succeeds.

This driver predates first git commit, and it turns out back then
of_platform_device_create worked differently than it does today.
So this is actually an old regression.

The appropriate function to undo of_platform_device_create now appears
to be of_platform_device_destroy, and switching to use this makes it
possible to unload and load the module as expected.

Signed-off-by: Nick Bowler <nbowler@draconx.ca>
Fixes: c6e126de43e7 ("of: Keep track of populated platform devices")
Cc: Pawel Moll <pawel.moll@arm.com>
---
 drivers/macintosh/therm_windtunnel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/macintosh/therm_windtunnel.c b/drivers/macintosh/therm_windtunnel.c
index 37cdc6931f6d..2576a53f247e 100644
--- a/drivers/macintosh/therm_windtunnel.c
+++ b/drivers/macintosh/therm_windtunnel.c
@@ -549,7 +549,7 @@ g4fan_exit( void )
 	platform_driver_unregister( &therm_of_driver );
 
 	if( x.of_dev )
-		of_device_unregister( x.of_dev );
+		of_platform_device_destroy(&x.of_dev->dev, NULL);
 }
 
 module_init(g4fan_init);
-- 
2.44.1

On Wed, 10 Jul 2024 23:54:17 -0400, Nick Bowler wrote:
> The of_device_unregister call in therm_windtunnel's module_exit procedure
> does not fully reverse the effects of of_platform_device_create in the
> module_init prodedure.  Once you unload this module, it is impossible
> to load it ever again since only the first of_platform_device_create
> call on the fan node succeeds.
> 
> This driver predates first git commit, and it turns out back then
> of_platform_device_create worked differently than it does today.
> So this is actually an old regression.
> 
> [...]

Applied to powerpc/next.

[1/1] macintosh/therm_windtunnel: fix module unload.
      https://git.kernel.org/powerpc/c/fd748e177194ebcbbaf98df75152a30e08230cc6

cheers