[PATCH] drm/radeon: silence GCC warning on 32 bit

[Paul Bolle <pebolle@tiscali.nl>]

Building radeon_ttm.o on 32 bit x86 triggers a warning:
    In file included from include/asm-generic/bug.h:13:0,
                     from [...]/arch/x86/include/asm/bug.h:38,
                     from include/linux/bug.h:4,
                     from include/drm/drm_mm.h:39,
                     from include/drm/drm_vma_manager.h:26,
                     from include/drm/ttm/ttm_bo_api.h:35,
                     from drivers/gpu/drm/radeon/radeon_ttm.c:32:
    drivers/gpu/drm/radeon/radeon_ttm.c: In function 'radeon_ttm_gtt_read':
    include/linux/kernel.h:712:17: warning: comparison of distinct pointer types lacks a cast [enabled by default]
      (void) (&_min1 == &_min2);  \
                     ^
    drivers/gpu/drm/radeon/radeon_ttm.c:938:22: note: in expansion of macro 'min'
       ssize_t cur_size = min(size, PAGE_SIZE - off);
                          ^

Silence this warning by casting "PAGE_SIZE - off" to size_t. Since
"PAGE_SIZE - off" is between 0 and PAGE_SIZE, and PAGE_SIZE is at most
21 bits wide while size_t is at least 32 bits wide, this should be safe.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
---
Compile tested only (on 32 and 64 bit x86).

 drivers/gpu/drm/radeon/radeon_ttm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
index 77f5b0c..5c87979 100644
--- a/drivers/gpu/drm/radeon/radeon_ttm.c
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
@@ -935,7 +935,7 @@ static ssize_t radeon_ttm_gtt_read(struct file *f, char __user *buf,
 	while (size) {
 		loff_t p = *pos / PAGE_SIZE;
 		unsigned off = *pos & ~PAGE_MASK;
-		ssize_t cur_size = min(size, PAGE_SIZE - off);
+		ssize_t cur_size = min(size, (size_t)(PAGE_SIZE - off));
 		struct page *page;
 		void *ptr;
 
-- 
1.8.5.3