From: Li RongQing <lirongqing@baidu.com>
The big_swap(p) macro was intended to swap bytes within 16-bit halves
of a 32-bit value. However, because the bitwise shift operators (<<, >>)
have higher precedence than the bitwise AND operator (&), the original
code failed to perform any shifting on the masked bits.
For example, 'p & 0xff00ff00 >> 8' was evaluated as 'p &
(0xff00ff00 >> 8)', effectively neutralizing the intended swap.
Fix this by adding parentheses to ensure the bitwise AND is performed
before the shift, correctly implementing the byte swap logic.
Fixes: 1461d66728648 ("staging: sm7xxfb: merge sm712fb with fbdev")
Signed-off-by: Li RongQing <lirongqing@baidu.com>
---
drivers/video/fbdev/sm712.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/video/fbdev/sm712.h b/drivers/video/fbdev/sm712.h
index c7ebf03..83fe25f 100644
--- a/drivers/video/fbdev/sm712.h
+++ b/drivers/video/fbdev/sm712.h
@@ -101,7 +101,7 @@ struct modeinit {
#define mmio_addr 0x00800000
#define seqw17() smtc_seqw(0x17, 0x30)
#define big_pixel_depth(p, d) {if (p == 24) {p = 32; d = 32; } }
-#define big_swap(p) ((p & 0xff00ff00 >> 8) | (p & 0x00ff00ff << 8))
+#define big_swap(p) (((p & 0xff00ff00) >> 8) | ((p & 0x00ff00ff) << 8))
#else
#define pal_rgb(r, g, b, val) val
#define big_addr 0
--
2.9.4