linux-kernel - [PATCH RFC] igb: Use TAI clock to reset PHC value

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Message-Id: <20230630154138.4041809-1-yoann.congal@smile.fr>
Date:   Fri, 30 Jun 2023 17:41:38 +0200
From:   Yoann Congal <yoann.congal@...le.fr>
To:     Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Tony Nguyen <anthony.l.nguyen@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Richard Cochran <richardcochran@...il.com>
Cc:     Yoann Congal <yoann.congal@...le.fr>,
        intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH RFC] igb: Use TAI clock to reset PHC value

The PHC is usually synchronised in TAI (from PTP). By resetting it with
the kernel TAI clock we avoid having to correct the PHC from REALTIME
(usually UTC) to TAI (37s as of today).

RFC: While this patch looks trivial and it does make linuxptp/ptp4l
complain about a driver bug:
  timed out while polling for tx timestamp
  increasing tx_timestamp_timeout may correct this issue, but it is likely caused by a driver bug
  port 1: send peer delay response failed

Increasing tx_timestamp_timeout to 1s does nothing different so I guess
the driver does indeed freeze with this change but I can't figure out
why... 

Do you have any idea/pointers? Thanks!

Signed-off-by: Yoann Congal <yoann.congal@...le.fr>
---
 drivers/net/ethernet/intel/igb/igb_ptp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/igb/igb_ptp.c b/drivers/net/ethernet/intel/igb/igb_ptp.c
index 15e57460e19ea..65e5de2ccb279 100644
--- a/drivers/net/ethernet/intel/igb/igb_ptp.c
+++ b/drivers/net/ethernet/intel/igb/igb_ptp.c
@@ -1526,12 +1526,12 @@ void igb_ptp_reset(struct igb_adapter *adapter)
 
 	/* Re-initialize the timer. */
 	if ((hw->mac.type == e1000_i210) || (hw->mac.type == e1000_i211)) {
-		struct timespec64 ts = ktime_to_timespec64(ktime_get_real());
+		struct timespec64 ts = ktime_to_timespec64(ktime_get_clocktai());
 
 		igb_ptp_write_i210(adapter, &ts);
 	} else {
 		timecounter_init(&adapter->tc, &adapter->cc,
-				 ktime_to_ns(ktime_get_real()));
+				 ktime_to_ns(ktime_get_clocktai()));
 	}
 out:
 	spin_unlock_irqrestore(&adapter->tmreg_lock, flags);
-- 
2.30.2