Migrate uses of sparse_keymap_free

[xylo04]

This no longer compiles on modern systems because sparse_keymap_free has been removed.

chris@helmhorn:~/git/panasonic-hbtn$ make
make -C /lib/modules/5.0.0-36-generic/build M=/home/chris/git/panasonic-hbtn modules
make[1]: Entering directory '/usr/src/linux-headers-5.0.0-36-generic'
  CC [M]  /home/chris/git/panasonic-hbtn/panasonic-hbtn.o
/home/chris/git/panasonic-hbtn/panasonic-hbtn.c: In function ‘acpi_pcc_init_input’:
/home/chris/git/panasonic-hbtn/panasonic-hbtn.c:170:5: error: implicit declaration of function ‘sparse_keymap_free’; did you mean ‘sparse_keymap_setup’? [-Werror=implicit-function-declaration]
     sparse_keymap_free(input_dev);
     ^~~~~~~~~~~~~~~~~~
     sparse_keymap_setup
cc1: some warnings being treated as errors
scripts/Makefile.build:291: recipe for target '/home/chris/git/panasonic-hbtn/panasonic-hbtn.o' failed
make[2]: *** [/home/chris/git/panasonic-hbtn/panasonic-hbtn.o] Error 1
Makefile:1614: recipe for target '_module_/home/chris/git/panasonic-hbtn' failed
make[1]: *** [_module_/home/chris/git/panasonic-hbtn] Error 2
make[1]: Leaving directory '/usr/src/linux-headers-5.0.0-36-generic'
Makefile:6: recipe for target 'all' failed
make: *** [all] Error 2

[ghostshadow]

yes, the sparse_keymap_free function has been removed without replacement, since it is no longer neccesary. (see comment and commit: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=79ffd5f98c11572c004d52f7ecd270ab680a7f72 )
For recent kernels it can be dropped, the only question is, if support for kernels before the memory management change is desired and how this would be implemented.

[xylo04]

For recent kernels it can be dropped

Is that to say that we can simply remove any calls to sparse_keymap_free? I suppose we would ideally have compiler directives to keep the calls in when an older kernel is used, but for now I'd settle for getting my own laptop usable.

[ghostshadow]

@xylo04 yes, that's what I did to get it working for me (see my fork, which I used for now as the target for my Archlinux PKGBUILD ).