Lines Matching +full:coexist +full:- +full:support
1 .. SPDX-License-Identifier: GPL-2.0
43 -------------------------------------------------------------
59 -------------------------------------------------------------------
72 ----------------------------------------------------------------------
117 require driver support and may not be available for all devices.
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
242 Support recv() cmsg for all timestamped packets. Control messages
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
358 byte range can coexist in multiple segments for protocols that
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 ----------------------------
437 feature. At least one field is non-zero at any time. Most timestamps
444 as linuxptp. For the PTP clock API, see Documentation/driver-api/ptp.rst.
481 is the first if ts[2] is non-zero, the second otherwise, in which
509 Reading from the error queue is always a non-blocking operation. To
545 the requested fine-grained filtering for incoming packets is not
552 support HWTSTAMP_FILTER_PTP_V2_EVENT, then it should generally always upscale
572 /* possible values for hwtstamp_config->tx_type */
590 /* possible values for hwtstamp_config->rx_filter */
610 --------------------------------------------------------
612 A driver which supports hardware time stamping must support the
615 should also support SIOCGHWTSTAMP.
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 ----------------------------------------------------------
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
752 to each individual MAC driver for PHY timestamping support. This entails:
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
777 (case in which explicit MAC driver support is indeed needed), but the
788 any PHY even if it doesn't support timestamping. In Linux, they are
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