Re: [stable:linux-4.9.y 66/1284] drivers/iio/magnetometer/ak8974.c:511:40: sparse: sparse: incorrect type in argument 2 (different base types)

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

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On Sat, 12 Dec 2020 15:21:10 +0100
Linus Walleij <linus.walleij@linaro.org> wrote:

> On Fri, Dec 11, 2020 at 3:27 PM kernel test robot <lkp@intel.com> wrote:
> 
> > "sparse warnings: (new ones prefixed by >>)"
> >    drivers/iio/magnetometer/ak8974.c:408:16: sparse: sparse: cast to restricted __le16
> >    drivers/iio/magnetometer/ak8974.c:485:29: sparse: sparse: cast to restricted __le16  
> > >> drivers/iio/magnetometer/ak8974.c:511:40: sparse: sparse: incorrect type in argument 2 (different base types) @@     expected signed short [usertype] *result @@     got restricted __le16 * @@  
> >    drivers/iio/magnetometer/ak8974.c:511:40: sparse:     expected signed short [usertype] *result
> >    drivers/iio/magnetometer/ak8974.c:511:40: sparse:     got restricted __le16 *  
> 
> I don't understand this, is sparse warning about implicit casting __le16
> to signed short or the other way around?
> 
> It seems to me to reasonable to allow anyway, I don't even see how
> we could avoid that except using explicit casts.

Looks to me like we didn't bother backporting a tidy up of the endian
types in here to 4.9. That changed the argument types to reflect that they
were arrays of __le16.


https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/iio/magnetometer/ak8974.c?h=v5.10&id=7f709dcda46105f617329630d97f5c97cea5b068

Personally I'm not that bothered about leaving this in place.
I don't think its an actual bug after all.

Jonathan

> 
> Yours,
> Linus Walleij