diff options
| author | Yannick Vignon <yannick.vignon@nxp.com> | 2022-02-03 17:00:25 +0100 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-02-03 13:54:19 -0800 |
| commit | 80d4609008e6d696a279e39ae7458c916fcd44c1 (patch) | |
| tree | 11559b54a09d07ee78ec76d9d00f914d3c28713b | |
| parent | 77b1b8b43ec3c060ecf7e926a92b0f8772171046 (diff) | |
| download | linux-80d4609008e6d696a279e39ae7458c916fcd44c1.tar.gz | |
net: stmmac: ensure PTP time register reads are consistent
Even if protected from preemption and interrupts, a small time window
remains when the 2 register reads could return inconsistent values,
each time the "seconds" register changes. This could lead to an about
1-second error in the reported time.
Add logic to ensure the "seconds" and "nanoseconds" values are consistent.
Fixes: 92ba6888510c ("stmmac: add the support for PTP hw clock driver")
Signed-off-by: Yannick Vignon <yannick.vignon@nxp.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://lore.kernel.org/r/20220203160025.750632-1-yannick.vignon@oss.nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c index 074e2cdfb0fa..a7ec9f4d46ce 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c @@ -145,15 +145,20 @@ static int adjust_systime(void __iomem *ioaddr, u32 sec, u32 nsec, static void get_systime(void __iomem *ioaddr, u64 *systime) { - u64 ns; - - /* Get the TSSS value */ - ns = readl(ioaddr + PTP_STNSR); - /* Get the TSS and convert sec time value to nanosecond */ - ns += readl(ioaddr + PTP_STSR) * 1000000000ULL; + u64 ns, sec0, sec1; + + /* Get the TSS value */ + sec1 = readl_relaxed(ioaddr + PTP_STSR); + do { + sec0 = sec1; + /* Get the TSSS value */ + ns = readl_relaxed(ioaddr + PTP_STNSR); + /* Get the TSS value */ + sec1 = readl_relaxed(ioaddr + PTP_STSR); + } while (sec0 != sec1); if (systime) - *systime = ns; + *systime = ns + (sec1 * 1000000000ULL); } static void get_ptptime(void __iomem *ptpaddr, u64 *ptp_time) |