Lines Matching +full:ts +full:- +full:attached
1 .. SPDX-License-Identifier: GPL-2.0
43 -------------------------------------------------------------
59 -------------------------------------------------------------------
72 ----------------------------------------------------------------------
138 over-report measurement, because the timestamp is generated when all
181 is derived from a per-socket u32 counter (that wraps). For datagram
204 cmsg->cmsg_level = SOL_SOCKET;
205 cmsg->cmsg_type = SCM_TS_OPT_ID;
206 cmsg->cmsg_len = CMSG_LEN(sizeof(__u32));
222 a timestamp with counter N-1. SOF_TIMESTAMPING_OPT_ID_TCP
272 received the packet and its length at layer 2. A valid (non-zero)
297 ignore the unexpected non-zero value. But it makes behavior subtly
324 cmsg->cmsg_level = SOL_SOCKET;
325 cmsg->cmsg_type = SO_TIMESTAMPING;
326 cmsg->cmsg_len = CMSG_LEN(sizeof(__u32));
344 -------------------------
354 correlating a timestamp with data is non-trivial. A range of bytes
383 relevant sequence number in skb_shinfo(skb)->tskey. Because an skbuff
392 autocork. After linux-4.7, a better way to prevent coalescing is
414 ----------------------------
422 struct timespec ts[3];
428 struct __kernel_timespec ts[3];
437 feature. At least one field is non-zero at any time. Most timestamps
438 are passed in ts[0]. Hardware timestamps are passed in ts[2].
440 ts[1] used to hold hardware timestamps converted to system time.
444 as linuxptp. For the PTP clock API, see Documentation/driver-api/ptp.rst.
449 in ts[0] when a real software timestamp is missing. This happens also
456 socket's error queue with the send timestamp(s) attached. A process
460 outgoing data packet with two ancillary messages attached.
481 is the first if ts[2] is non-zero, the second otherwise, in which
482 case the timestamp is stored in ts[0].
509 Reading from the error queue is always a non-blocking operation. To
524 implicitly defined. ts[0] holds a software timestamp if set, ts[1]
525 is again deprecated and ts[2] holds a hardware timestamp if set.
545 the requested fine-grained filtering for incoming packets is not
572 /* possible values for hwtstamp_config->tx_type */
590 /* possible values for hwtstamp_config->rx_filter */
610 --------------------------------------------------------
630 - In hard_start_xmit(), check if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)
631 is set no-zero. If yes, then the driver is expected to do hardware time
633 - If this is possible for the skb and requested, then declare
635 SKBTX_IN_PROGRESS in skb_shinfo(skb)->tx_flags , e.g. with::
637 skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
643 - Driver should call skb_tx_timestamp() as close to passing sk_buff to hardware
646 - As soon as the driver has sent the packet and/or obtained a
658 ----------------------------------------------------------
677 When a DSA switch is attached to a host port, PTP synchronization has to
689 handling in the driver for the host port it is attached to. However, when the
699 - ``.port_txtstamp()``: a hook called prior to the transmission of
701 This is required for two-step timestamping, since the hardware
704 packet so that it can re-enqueue the packet back into the socket's
707 in skb->cb and enqueue a tx skb queue. Typically, a switch will have a
710 key-value pairs of PTP sequence ID/message type/domain number and the
718 One-step TX timestamping do not require packet cloning, since there is
719 no follow-up message required by the PTP protocol (because the
722 to be re-enqueued into its socket's error queue.
724 - ``.port_rxtstamp()``: On RX, the BPF classifier is run by DSA to
729 timestamps might either be available in-band (through metadata in the
730 DSA header, or attached in other ways to the packet), or out-of-band
746 mii_timestamper`` and add a pointer to it in ``phydev->mii_ts``. The presence
754 - Checking, in ``.ndo_eth_ioctl``, whether ``phy_has_hwtstamp(netdev->phydev)``
758 - On RX, special intervention may or may not be needed, depending on the
761 ``skb_defer_rx_timestamp(skb)`` is necessary or not - and if it is, don't
763 enabled, and ``skb->dev->phydev->mii_ts`` exists, its ``.rxtstamp()`` hook
774 - On TX, again, special intervention might or might not be needed. The
775 function that calls the ``mii_ts->txtstamp()`` hook is named
796 Stacked PHCs, especially DSA (but not only) - since that doesn't require any
798 all possible code paths - is that they uncover bugs which were impossible to
802 skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
813 the ``.ndo_eth_ioctl`` ("``priv->hwtstamp_tx_enabled == true``") and the
814 current skb requires a TX timestamp ("``skb_shinfo(skb)->tx_flags &
816 "``skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS``" flag. Note: as
824 "``skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS``" was set. With a stacked
831 "``skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS``", but also for
832 "``priv->hwtstamp_tx_enabled == true``". Because the rest of the system ensures