From: Barry Song<Baohua.Song@xxxxxxx>
Any write request to /dev/cma_test will let the module to allocate memory from
CMA, for example:
1st time
$ echo 1024> /dev/cma_test
will require cma_test to request 1MB(1024KB)
2nd time
$ echo 2048> /dev/cma_test
will require cma_test to request 2MB(2048KB)
Any read request to /dev/cma_test will let the module to free the 1st valid
memory from CMA, for example:
1st time
$ cat /dev/cma_test
will require cma_test to free the 1MB allocated in the first write request
2nd time
$ cat /dev/cma_test
will require cma_test to free the 2MB allocated in the second write request