Re: [PATCH 31/34] spi: remove incorrect of_match_ptr annotations

["Arnd Bergmann" <arnd@xxxxxxxx>]

On Wed, Apr 3, 2024, at 23:13, Andy Shevchenko wrote:
> Wed, Apr 03, 2024 at 11:05:51PM +0200, Uwe Kleine-König kirjoitti:
>> On Wed, Apr 03, 2024 at 10:56:58AM +0100, Mark Brown wrote:
>> > On Wed, Apr 03, 2024 at 10:06:49AM +0200, Arnd Bergmann wrote:
>> > 
>> > > These appear to all be copied from the same original driver, so fix them at the
>> > > same time by removing the unnecessary of_match_ptr() annotation. As far as I
>> > > can tell, all these drivers are only actually used on configurations that
>> > > have CONFIG_OF enabled.
>> > 
>> > Why are we not fixing of_match_ptr() here, or at least adding the ifdefs
>> > in case someone does end up wanting to run without OF?
>> 
>> Fixing of_match_ptr =
>> 
>> diff --git a/include/linux/of.h b/include/linux/of.h
>> index a0bedd038a05..d980bccffda0 100644
>> --- a/include/linux/of.h
>> +++ b/include/linux/of.h
>> @@ -890,7 +890,7 @@ static inline const void *of_device_get_match_data(const struct device *dev)
>>  	return NULL;
>>  }
>>  
>> -#define of_match_ptr(_ptr)	NULL
>> +#define of_match_ptr(_ptr)	(0 ? (_ptr) : NULL)

This would require removing several hundred "#ifdef CONFIG_OF"
checks around the of_device_id tables at the same time
unfortunately. Most of those are completely unnecessary, so
if we wanted to remove those, we should remove the of_match_ptr()
instances at the same time.

>>  #define of_match_node(_matches, _node)	NULL
>>  #endif /* CONFIG_OF */
>>  
>> ?
>> 
>> Assuming this helps, I agree this would be the better fix.
>
> Why? I mean why do we need to even have this API? It's always
> good to know which devices are supported by the module even
> if you have no need in such support or it's not compiled in.
> One of the reasons why is to be able to google for compatible hardware,
> for example.

As far as I can tell, the of_match_ptr() helper was a historic
mistake, it makes pretty much no sense in its current form.

The version that Uwe proposes would have made sense but we
can't change it now.

      Arnd