[PATCH] blackfin: define dummy pgprot_writecombine for !MMU

[Sudip Mukherjee]

blackfin allmodconfig build fails with the error:

../sound/core/pcm_native.c: In function 'snd_pcm_lib_default_mmap':
../sound/core/pcm_native.c:3386:24: error: implicit declaration of function 'pgprot_writecombine' [-Werror=implicit-function-declaration]
   area->vm_page_prot = pgprot_writecombine(area->vm_page_prot);
                        ^
../sound/core/pcm_native.c:3386:22: error: incompatible types when assigning to type 'pgprot_t {aka struct <anonymous>}' from type 'int'
   area->vm_page_prot = pgprot_writecombine(area->vm_page_prot);
                      ^

When !MMU, asm-generic will not define default pgprot_writecombine, so
blackfin needs to define it by itself.

Signed-off-by: Sudip Mukherjee <sudip@xxxxxxxxxxxxxxx>
---

Build log is at
https://travis-ci.org/sudipm-mukherjee/parport/jobs/108209182

The patch idea is from:
65b9ab888cd7 ("arch/c6x/include/asm/pgtable.h: define dummy pgprot_writecombine for !MMU")

 arch/blackfin/include/asm/pgtable.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/blackfin/include/asm/pgtable.h b/arch/blackfin/include/asm/pgtable.h
index b88a155..c1ee3d6 100644
--- a/arch/blackfin/include/asm/pgtable.h
+++ b/arch/blackfin/include/asm/pgtable.h
@@ -97,6 +97,8 @@ extern unsigned long get_fb_unmapped_area(struct file *filp, unsigned long,
 					  unsigned long);
 #define HAVE_ARCH_FB_UNMAPPED_AREA
 
+#define pgprot_writecombine pgprot_noncached
+
 #include <asm-generic/pgtable.h>
 
 #endif				/* _BLACKFIN_PGTABLE_H */
-- 
1.9.1