fbdev: sm712: Fix operator precedence in big_swap macro

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")
Cc: stable@vger.kernel.org
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/drivers/video/fbdev/sm712.h b/drivers/video/fbdev/sm712.h
index c7ebf03b8d5378b2536123a7c957cbabc17c41ee..83fe25fc61f2c4d1185d736b7751a027e009d2bd 100644 (file)
--- 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