ODROID-C2: gpu/arm: hack to force the memory page writable

This patch is the hack to force the memory pages allocated by the ump driver
to be writable such that they cannot have an error 'permission denied' when
'mmap()' is called.

Change-Id: I6917b0c36d93b0bf24a5a81d68c46c1802e2f9a5
Signed-off-by: Dongjin Kim <tobetter@gmail.com>

drivers/gpu/arm/ump/linux/ump_kernel_linux.c

@@ -321,10 +321,16 @@ static int ump_file_ioctl(struct inode *inode, struct file *filp, unsigned int c
  break;
 
  case UMP_IOC_ALLOCATE :
+#if defined(CONFIG_ARCH_MESON64_ODROIDC2)
+ mapping_allow_writable(filp->f_mapping);
+#endif
  err = ump_allocate_wrapper((u32 __user *)argument, session_data);
  break;
 
  case UMP_IOC_RELEASE:
+#if defined(CONFIG_ARCH_MESON64_ODROIDC2)
+ mapping_deny_writable(filp->f_mapping);
+#endif
  err = ump_release_wrapper((u32 __user *)argument, session_data);
  break;