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author | Wang Haitao <wang.haitao1@zte.com.cn> | 2013-08-22 11:32:38 (GMT) |
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committer | Brian Norris <computersforpeace@gmail.com> | 2013-11-07 07:32:59 (GMT) |
commit | a4d62babf988fe5dfde24437fa135ef147bc7aa0 (patch) | |
tree | 6f34c5f7eaafcb6d76273845ebfaeb88bc377f20 /drivers/mfd/vexpress-sysreg.c | |
parent | f83c3838b9146b891d0405d3a83660e8f6aed02f (diff) | |
download | linux-fsl-qoriq-a4d62babf988fe5dfde24437fa135ef147bc7aa0.tar.xz |
mtd: map: fixed bug in 64-bit systems
Hardware:
CPU: XLP832,the 64-bit OS
NOR Flash:S29GL128S 128M
Software:
Kernel:2.6.32.41
Filesystem:JFFS2
When writing files, errors appear:
Write len 182 but return retlen 180
Write of 182 bytes at 0x072c815c failed. returned -5, retlen 180
Write len 186 but return retlen 184
Write of 186 bytes at 0x072caff4 failed. returned -5, retlen 184
These errors exist only in 64-bit systems,not in 32-bit systems. After analysis, we
found that the left shift operation is wrong in map_word_load_partial. For instance:
unsigned char buf[3] ={0x9e,0x3a,0xea};
map_bankwidth(map) is 4;
for (i=0; i < 3; i++) {
int bitpos;
bitpos = (map_bankwidth(map)-1-i)*8;
orig.x[0] &= ~(0xff << bitpos);
orig.x[0] |= buf[i] << bitpos;
}
The value of orig.x[0] is expected to be 0x9e3aeaff, but in this situation(64-bit
System) we'll get the wrong value of 0xffffffff9e3aeaff due to the 64-bit sign
extension:
buf[i] is defined as "unsigned char" and the left-shift operation will convert it
to the type of "signed int", so when left-shift buf[i] by 24 bits, the final result
will get the wrong value: 0xffffffff9e3aeaff.
If the left-shift bits are less than 24, then sign extension will not occur. Whereas
the bankwidth of the nor flash we used is 4, therefore this BUG emerges.
Signed-off-by: Pang Xunlei <pang.xunlei@zte.com.cn>
Signed-off-by: Zhang Yi <zhang.yi20@zte.com.cn>
Signed-off-by: Lu Zhongjun <lu.zhongjun@zte.com.cn>
Cc: <stable@vger.kernel.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Diffstat (limited to 'drivers/mfd/vexpress-sysreg.c')
0 files changed, 0 insertions, 0 deletions