* FAILED: patch "[PATCH] net: stmmac: ensure PTP time register reads are consistent" failed to apply to 4.9-stable tree
@ 2022-02-06 12:45 gregkh
0 siblings, 0 replies; only message in thread
From: gregkh @ 2022-02-06 12:45 UTC (permalink / raw)
To: yannick.vignon, kuba, rmk+kernel; +Cc: stable
The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 80d4609008e6d696a279e39ae7458c916fcd44c1 Mon Sep 17 00:00:00 2001
From: Yannick Vignon <yannick.vignon@nxp.com>
Date: Thu, 3 Feb 2022 17:00:25 +0100
Subject: [PATCH] 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>
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)
^ permalink raw reply related [flat|nested] only message in thread
only message in thread, other threads:[~2022-02-06 12:46 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-02-06 12:45 FAILED: patch "[PATCH] net: stmmac: ensure PTP time register reads are consistent" failed to apply to 4.9-stable tree gregkh
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.