> -----Original Message-----
> From: Korba, Przemyslaw <[email protected]>
> Sent: Monday, October 26, 2026 5:37 PM
> To: [email protected]
> Cc: Nguyen, Anthony L <[email protected]>; Kitszel, Przemyslaw
> <[email protected]>; Loktionov, Aleksandr
> <[email protected]>; Kubalewski, Arkadiusz
> <[email protected]>; Ilichev, Konstantin
> <[email protected]>; Korba, Przemyslaw
> <[email protected]>; Olech, Milena <[email protected]>
> Subject: [PATCH iwl-net 2/2] ixgbe: fix Rx hardware timestamping for
> VLAN tagged packets
>
> Timestamp in packet (TSIP) is enabled by TSYNCRXCTL.TSIP_UT_EN, which
> covers untagged frames only. VLAN tagged frames need the per user
> priority mask in TSYNCRXCTL[31:24], which was never set, so they carry
> no timestamp and IXGBE_RXD_STAT_TSIP stays clear.
> ixgbe_ptp_rx_hwtstamp() then falls back to RXSTMPL/RXSTMPH, which hold a
> single timestamp latched until read, so a tagged frame is given a stale
> timestamp left by an earlier packet.
> Filter type TYPE_ALL also clears IXGBE_FLAG_RX_HWTSTAMP_IN_REGISTER,
> which gates ixgbe_ptp_rx_hang(), so a stuck latch is never cleared
> either.
>
> Set TSIP_UP_MASK along with TSIP_UT_EN, add the missing register
> definition, and extend the clear mask so the new bits are cleared when
> Rx timestamping is disabled.
>
> This covers 802.1Q priorities 0-7. The fallback itself is left in place:
> any frame class the hardware reports with STAT_TS but without TSIP, such
> as a QinQ outer tag, would still be given a latched timestamp.
> Suppressing the fallback outside IN_REGISTER mode is a separate change.
>
> Observed on a machine in real use: ptp4l over an 802.1Q interface never
> converged, reporting path delay between 444 ns and 31 us and even
> negative values, while the untagged interface held a stable 3 us.
> Reproduced by adding a VLAN interface and running ptp4l on it, with no
> kernel modification and no error injection. Tested against that
> reproducer on two Intel E610 10GBASE-T ports connected back to back at
> 10 Gbps, where ptp4l now converges over VLAN as it does untagged. No
> kernel selftests cover Rx hardware timestamping.
>
> Fixes: a9763f3cb54c ("ixgbe: Update PTP to support X550EM_x devices")
> Signed-off-by: Przemyslaw Korba <[email protected]>
> Reviewed-by: Milena Olech <[email protected]>
> ---
> drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c | 6 ++++--
> drivers/net/ethernet/intel/ixgbe/ixgbe_type.h | 1 +
> 2 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c
> b/drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c
> index 8dc6a009b62c..4be7450beea8 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c
> @@ -1084,7 +1084,8 @@ static int ixgbe_ptp_set_timestamp_mode(struct
> ixgbe_adapter *adapter,
>
> tsync_rx_ctl = IXGBE_TSYNCRXCTL_ENABLED |
> IXGBE_TSYNCRXCTL_TYPE_ALL |
> - IXGBE_TSYNCRXCTL_TSIP_UT_EN;
> + IXGBE_TSYNCRXCTL_TSIP_UT_EN |
> + IXGBE_TSYNCRXCTL_TSIP_UP_MASK;
> config->rx_filter = HWTSTAMP_FILTER_ALL;
> aflags |= IXGBE_FLAG_RX_HWTSTAMP_ENABLED;
> aflags &= ~IXGBE_FLAG_RX_HWTSTAMP_IN_REGISTER;
> @@ -1112,7 +1113,8 @@ static int ixgbe_ptp_set_timestamp_mode(struct
> ixgbe_adapter *adapter,
> /* enable/disable RX */
> regval = IXGBE_READ_REG(hw, IXGBE_TSYNCRXCTL);
> regval &= ~(IXGBE_TSYNCRXCTL_ENABLED | IXGBE_TSYNCRXCTL_TYPE_MASK
> |
> - IXGBE_TSYNCRXCTL_TSIP_UT_EN);
> + IXGBE_TSYNCRXCTL_TSIP_UT_EN |
> + IXGBE_TSYNCRXCTL_TSIP_UP_MASK);
> regval |= tsync_rx_ctl;
> IXGBE_WRITE_REG(hw, IXGBE_TSYNCRXCTL, regval);
>
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h
> b/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h
> index c2bd104e64bf..78067b49216d 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h
> @@ -2283,6 +2283,7 @@ enum {
> #define IXGBE_TSYNCRXCTL_TYPE_EVENT_V2 0x0A
> #define IXGBE_TSYNCRXCTL_ENABLED 0x00000010 /* Rx Timestamping enabled
> */
> #define IXGBE_TSYNCRXCTL_TSIP_UT_EN 0x00800000 /* Rx Timestamp in
> Packet */
> +#define IXGBE_TSYNCRXCTL_TSIP_UP_MASK 0xFF000000 /* Rx Timestamp UP
> Mask */
>
> #define IXGBE_TSIM_TXTS 0x00000002
>
> --
> 2.43.0
Reviewed-by: Aleksandr Loktionov <[email protected]>
