[PATCH] DRM: Fix build error in include/drm/ttm/ttm_memory.h

[Ralf Baechle <ralf@linux-mips.org>]

include/drm/ttm/ttm_memory.h uses struct page * without having included
the required headers or a forward declaration resulting in the following
build error for mtx1_defconfig on Linus' master branch, possibly others:

  CC [M]  drivers/gpu/drm/ttm/ttm_memory.o
In file included from /home/ralf/src/linux/linux-mips/drivers/gpu/drm/ttm/ttm_memory.c:28:
/home/ralf/src/linux/linux-mips/include/drm/ttm/ttm_memory.h:154: warning: ‘struct page’ declared inside parameter list
/home/ralf/src/linux/linux-mips/include/drm/ttm/ttm_memory.h:154: warning: its scope is only this definition or declaration, which is probably not what you want
/home/ralf/src/linux/linux-mips/include/drm/ttm/ttm_memory.h:156: warning: ‘struct page’ declared inside parameter list
/home/ralf/src/linux/linux-mips/drivers/gpu/drm/ttm/ttm_memory.c:537: error: conflicting types for ‘ttm_mem_global_alloc_page’
/home/ralf/src/linux/linux-mips/include/drm/ttm/ttm_memory.h:152: note: previous declaration of ‘ttm_mem_global_alloc_page’ was here
/home/ralf/src/linux/linux-mips/drivers/gpu/drm/ttm/ttm_memory.c:560: error: conflicting types for ‘ttm_mem_global_free_page’
/home/ralf/src/linux/linux-mips/include/drm/ttm/ttm_memory.h:155: note: previous declaration of ‘ttm_mem_global_free_page’ was here
make[6]: *** [drivers/gpu/drm/ttm/ttm_memory.o] Error 1
make[5]: *** [drivers/gpu/drm/ttm] Error 2
make[4]: *** [drivers/gpu/drm] Error 2
make[3]: *** [drivers/gpu] Error 2
make[2]: *** [drivers] Error 2
make[1]: *** [sub-make] Error 2
make: *** [all] Error 2

Fixed by adding a forward declaration.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

 include/drm/ttm/ttm_memory.h |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/include/drm/ttm/ttm_memory.h b/include/drm/ttm/ttm_memory.h
index 6983a7c..95355ee 100644
--- a/include/drm/ttm/ttm_memory.h
+++ b/include/drm/ttm/ttm_memory.h
@@ -143,6 +143,8 @@ static inline void ttm_mem_unregister_shrink(struct ttm_mem_global *glob,
 	spin_unlock(&glob->lock);
 }
 
+struct page;
+
 extern int ttm_mem_global_init(struct ttm_mem_global *glob);
 extern void ttm_mem_global_release(struct ttm_mem_global *glob);
 extern int ttm_mem_global_alloc(struct ttm_mem_global *glob, uint64_t memory,