drm/ttm: Fix a potential comparison of structs.

On some architectures the comparison may cause a compilation failure.

Original partial fix Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Pekka Paalanen <pq@iki.fi>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/ttm/ttm_bo_util.c

@@ -150,7 +150,7 @@ static int ttm_copy_io_ttm_page(struct ttm_tt *ttm, void *src,
 #ifdef CONFIG_X86
 	dst = kmap_atomic_prot(d, KM_USER0, prot);
 #else
-	if (prot != PAGE_KERNEL)
+	if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL))
 		dst = vmap(&d, 1, 0, prot);
 	else
 		dst = kmap(d);
@@ -163,7 +163,7 @@ static int ttm_copy_io_ttm_page(struct ttm_tt *ttm, void *src,
 #ifdef CONFIG_X86
 	kunmap_atomic(dst, KM_USER0);
 #else
-	if (prot != PAGE_KERNEL)
+	if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL))
 		vunmap(dst);
 	else
 		kunmap(d);
@@ -186,7 +186,7 @@ static int ttm_copy_ttm_io_page(struct ttm_tt *ttm, void *dst,
 #ifdef CONFIG_X86
 	src = kmap_atomic_prot(s, KM_USER0, prot);
 #else
-	if (prot != PAGE_KERNEL)
+	if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL))
 		src = vmap(&s, 1, 0, prot);
 	else
 		src = kmap(s);
@@ -199,7 +199,7 @@ static int ttm_copy_ttm_io_page(struct ttm_tt *ttm, void *dst,
 #ifdef CONFIG_X86
 	kunmap_atomic(src, KM_USER0);
 #else
-	if (prot != PAGE_KERNEL)
+	if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL))
 		vunmap(src);
 	else
 		kunmap(s);