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fbdev: sm712: Fix operator precedence in big_swap macro

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commit 5dbe5b65df upstream.

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: 1461d66728 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Li RongQing
2026-07-24 16:03:31 +02:00
committed by Greg Kroah-Hartman
parent 2952767e39
commit 2003759092
1 changed files with 1 additions and 1 deletions
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drivers/video/fbdev/sm712.h
+1 -1
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@@ -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