From: Roland Hii roland.king.guan.hii@intel.com
[ Upstream commit a1e5388b4d5fc78688e5e9ee6641f779721d6291 ]
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: ba1ffd74df74 ("stmmac: fix PTP support for GMAC4") Signed-off-by: Roland Hii roland.king.guan.hii@intel.com Signed-off-by: Ong Boon Leong boon.leong.ong@intel.com Signed-off-by: Voon Weifeng weifeng.voon@intel.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c @@ -125,7 +125,7 @@ static int stmmac_adjust_systime(void __ * programmed with (2^32 – <new_sec_value>) */ if (gmac4) - sec = (100000000ULL - sec); + sec = -sec;
value = readl(ioaddr + PTP_TCR); if (value & PTP_TCR_TSCTRLSSR)