Commit ac086d4c authored by Roland Hii's avatar Roland Hii Committed by Greg Kroah-Hartman

net: stmmac: fixed new system time seconds value calculation

[ Upstream commit a1e5388b ]

When ADDSUB bit is set, the system time seconds field is calculated as
the complement of the seconds part of the update value.

For example, if 3.000000001 seconds need to be subtracted from the
system time, this field is calculated as
2^32 - 3 = 4294967296 - 3 = 0x100000000 - 3 = 0xFFFFFFFD

Previously, the 0x100000000 is mistakenly written as 100000000.

This is further simplified from
  sec = (0x100000000ULL - sec);
to
  sec = -sec;

Fixes: ba1ffd74 ("stmmac: fix PTP support for GMAC4")
Signed-off-by: default avatarRoland Hii <roland.king.guan.hii@intel.com>
Signed-off-by: default avatarOng Boon Leong <boon.leong.ong@intel.com>
Signed-off-by: default avatarVoon Weifeng <weifeng.voon@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 505c9258
......@@ -122,7 +122,7 @@ static int adjust_systime(void __iomem *ioaddr, u32 sec, u32 nsec,
* programmed with (2^32 – <new_sec_value>)
*/
if (gmac4)
sec = (100000000ULL - sec);
sec = -sec;
value = readl(ioaddr + PTP_TCR);
if (value & PTP_TCR_TSCTRLSSR)
......
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