From 34270f5f6f1bcc2dc9d2e5aa28147667425cc424 Mon Sep 17 00:00:00 2001 From: Fugang Duan Date: Fri, 5 Jun 2015 17:22:08 +0800 Subject: [PATCH] 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 Signed-off-by: Frank Li Signed-off-by: David S. Miller --- drivers/net/ethernet/freescale/fec_ptp.c | 1 + 1 file changed, 1 insertion(+) 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); -- 2.39.5