Re: [PATCH V6 4/7] OF: properties: Implement get_match_data() callback

["Lothar Waßmann" <LW@KARO-electronics.de>]

Hi,

On Thu, 7 Dec 2017 12:50:50 -0500 Sinan Kaya wrote:
> On 12/7/2017 10:20 AM, Lothar Waßmann wrote:
> > Hi,
> > 
> > On Thu, 7 Dec 2017 09:45:31 -0500 Sinan Kaya wrote:
> >> On 12/7/2017 8:10 AM, Lothar Waßmann wrote:
> >>>> +void *of_fwnode_get_match_data(const struct fwnode_handle *fwnode,
> >>>> +			       struct device *dev)
> >>> Shouldn't this be 'const void *of_fwnode_get_match_data
> >>
> >> OF keeps the driver data as a (const void*) internally. ACPI keeps the
> >> driver data as kernel_ulong_t in struct acpi_device_id.
> >>
> >> I tried to find the middle ground here by converting output to void*
> >> but not keeping const.
> >>
> > It should be no problem to cast a (const void *) to an unsigned long
> > data type (without const qualifier).
> > 
> 
> It is the other way around. If I change this API to return a a (const void*),
> the device_get_match_data() function need to return a (const void *).
> 
> While implementing the ACPI piece, I have to convert an unsigned long to
> (const void *) in ACPI code so that the APIs are compatible.
> 
That's true, but I don't see any problem with that. Your
device_get_match_data() is merely a wrapper around of_device_get_match_data()
which returns a const pointer. I see no reason to change this to a
non-const pointer by the wrapper function.


Lothar Waßmann