Re: [linux-next:master 1797/8629] drivers/tty/ipwireless/hardware.c:872:43: sparse: sparse: incorrect type in initializer (different base types)

[Arnd Bergmann <arnd@arndb.de>]

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On Thu, Sep 17, 2020 at 11:10 PM kernel test robot <lkp@intel.com> wrote:
>
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   860461e4fcaa76200d2d1a53523e0ff7be92e6e8
> commit: 98c2922ec8f0601321428be8c59ae1df255478d1 [1797/8629] ARM: s3c24xx: simplify mach/io.h
> config: arm-randconfig-s031-20200917 (attached as .config)
> compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0
> reproduce:
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # apt-get install sparse
>         # sparse version: v0.6.2-201-g24bdaac6-dirty
>         git checkout 98c2922ec8f0601321428be8c59ae1df255478d1
>         # save the attached .config to linux build tree
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=arm
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
>
>
> sparse warnings: (new ones prefixed by >>)
>
>    drivers/tty/ipwireless/hardware.c:431:25: sparse: sparse: cast from restricted __le16
>    drivers/tty/ipwireless/hardware.c:445:25: sparse: sparse: cast from restricted __le16
> >> drivers/tty/ipwireless/hardware.c:872:43: sparse: sparse: incorrect type in initializer (different base types) @@     expected restricted __le16 [usertype] raw_data @@     got unsigned short [usertype] __v @@
>    drivers/tty/ipwireless/hardware.c:872:43: sparse:     expected restricted __le16 [usertype] raw_data
> >> drivers/tty/ipwireless/hardware.c:872:43: sparse:     got unsigned short [usertype] __v
>    drivers/tty/ipwireless/hardware.c:889:43: sparse: sparse: incorrect type in initializer (different base types) @@     expected restricted __le16 [usertype] raw_data @@     got unsigned short [usertype] __v @@
>    drivers/tty/ipwireless/hardware.c:889:43: sparse:     expected restricted __le16 [usertype] raw_data
>    drivers/tty/ipwireless/hardware.c:889:43: sparse:     got unsigned short [usertype] __v

I think it's a preexisting bug that we already get a warning for in other
configurations, now the same warning also appears on s3c24xx.

The bug was already in the original merge of the driver:

+               for (i = 0; i < len; i += 2) {
+                       __le16 raw_data = inw(hw->base_port + IODMADPR);
+                       unsigned short data = le16_to_cpu(raw_data);
+
+                       pkt[i] = (unsigned char) data;
+                       pkt[i + 1] = (unsigned char) (data >> 8);
+               }

This reimplements the insw() function with a total of three byte swaps on
big-endian machines. I assume an even number of byte swaps  (as done
by inw) would have been needed to make it work on big-endian, but this
depends on the actual hardware implementation.

It seems unlikely that there are any big-endian machines with pc-card
slots that would want to use this hardware.

       Arnd