From: Fugang Duan <[email protected]>
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 <[email protected]>
Signed-off-by: Frank Li <[email protected]>
---
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 2daf42e..9eb81fa 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);
--
1.7.8
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