diff options
| author | Fugang Duan <b38611@freescale.com> | 2015-06-05 11:22:08 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-06-08 00:30:42 +0200 |
| commit | 34270f5f6f1bcc2dc9d2e5aa28147667425cc424 (patch) | |
| tree | cbe559f5b5ba3d9b8c04541a177d99ef25a7ca11 | |
| parent | net: ll_temac: Remove sparse warnings (diff) | |
| download | linux-34270f5f6f1bcc2dc9d2e5aa28147667425cc424.tar.xz linux-34270f5f6f1bcc2dc9d2e5aa28147667425cc424.zip | |
net: fec: ptp: correct the ENET_ATCOR value
The current driver adjust freq formula is:
fe * diff = ppb * pc
Note:
fe: ENET ref clock frequency in Hz
diff = inc_corr - inc: difference between default increment and correction increment
ppb: parts per billion adjustment from base
pc: correction period (in number of fe clock cycles)
The correction increment will be used after N cycles of regular increments,
not every N cycles (with N being the correction period). For example, set ENET_ATCOR=4,
INC=8, INC_CORR=9, there will be 4 increments of 8 (ENET_ATINC[INC]) , followed by 1
increment of 9 (ENET_ATINC[INC_CORR]).
So, the correct formula is:
fe * diff = ppb * (pc + 1)
For ENET_ATCOR, a value 0 disables the correction counter and no corrections occur.
So base on the origin formula, set pc = pc > 1 ? pc - 1 : pc.
Signed-off-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Frank Li <Frank.Li@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/net/ethernet/freescale/fec_ptp.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/net/ethernet/freescale/fec_ptp.c b/drivers/net/ethernet/freescale/fec_ptp.c index a583d89b13c4..a15663ad7f5e 100644 --- a/drivers/net/ethernet/freescale/fec_ptp.c +++ b/drivers/net/ethernet/freescale/fec_ptp.c @@ -353,6 +353,7 @@ static int fec_ptp_adjfreq(struct ptp_clock_info *ptp, s32 ppb) tmp = readl(fep->hwp + FEC_ATIME_INC) & FEC_T_INC_MASK; tmp |= corr_ns << FEC_T_INC_CORR_OFFSET; writel(tmp, fep->hwp + FEC_ATIME_INC); + corr_period = corr_period > 1 ? corr_period - 1 : corr_period; writel(corr_period, fep->hwp + FEC_ATIME_CORR); /* dummy read to update the timer. */ timecounter_read(&fep->tc); |