Lines Matching +full:compound +full:- +full:device
1 .. SPDX-License-Identifier: GPL-2.0
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59 -------------------------------------------------------------------
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106 are generated just after a device driver hands a packet to the
115 are generated in the device driver as close as possible, but always
138 over-report measurement, because the timestamp is generated when all
181 is derived from a per-socket u32 counter (that wraps). For datagram
208 a timestamp with counter N-1. SOF_TIMESTAMPING_OPT_ID_TCP
232 is to correlate packets with their egress device, by enabling socket
258 received the packet and its length at layer 2. A valid (non-zero)
283 ignore the unexpected non-zero value. But it makes behavior subtly
310 cmsg->cmsg_level = SOL_SOCKET;
311 cmsg->cmsg_type = SO_TIMESTAMPING;
312 cmsg->cmsg_len = CMSG_LEN(sizeof(__u32));
330 -------------------------
336 when all bytes have reached the device driver, regardless of how
340 correlating a timestamp with data is non-trivial. A range of bytes
369 relevant sequence number in skb_shinfo(skb)->tskey. Because an skbuff
378 autocork. After linux-4.7, a better way to prevent coalescing is
400 ----------------------------
423 feature. At least one field is non-zero at any time. Most timestamps
427 Instead, expose the hardware clock device on the NIC directly as
430 as linuxptp. For the PTP clock API, see Documentation/driver-api/ptp.rst.
467 is the first if ts[2] is non-zero, the second otherwise, in which
495 Reading from the error queue is always a non-blocking operation. To
517 Hardware time stamping must also be initialized for each device driver
527 Desired behavior is passed into the kernel and to a specific device by
531 the requested fine-grained filtering for incoming packets is not
558 /* possible values for hwtstamp_config->tx_type */
576 /* possible values for hwtstamp_config->rx_filter */
595 3.1 Hardware Timestamping Implementation: Device Drivers
596 --------------------------------------------------------
616 - In hard_start_xmit(), check if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)
617 is set no-zero. If yes, then the driver is expected to do hardware time
619 - If this is possible for the skb and requested, then declare
621 SKBTX_IN_PROGRESS in skb_shinfo(skb)->tx_flags , e.g. with::
623 skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
629 - Driver should call skb_tx_timestamp() as close to passing sk_buff to hardware
632 - As soon as the driver has sent the packet and/or obtained a
644 ----------------------------------------------------------
685 - ``.port_txtstamp()``: a hook called prior to the transmission of
687 This is required for two-step timestamping, since the hardware
690 packet so that it can re-enqueue the packet back into the socket's
693 in skb->cb and enqueue a tx skb queue. Typically, a switch will have a
696 key-value pairs of PTP sequence ID/message type/domain number and the
704 One-step TX timestamping do not require packet cloning, since there is
705 no follow-up message required by the PTP protocol (because the
708 to be re-enqueued into its socket's error queue.
710 - ``.port_rxtstamp()``: On RX, the BPF classifier is run by DSA to
715 timestamps might either be available in-band (through metadata in the
716 DSA header, or attached in other ways to the packet), or out-of-band
732 mii_timestamper`` and add a pointer to it in ``phydev->mii_ts``. The presence
740 - Checking, in ``.ndo_eth_ioctl``, whether ``phy_has_hwtstamp(netdev->phydev)``
744 - On RX, special intervention may or may not be needed, depending on the
747 ``skb_defer_rx_timestamp(skb)`` is necessary or not - and if it is, don't
749 enabled, and ``skb->dev->phydev->mii_ts`` exists, its ``.rxtstamp()`` hook
760 - On TX, again, special intervention might or might not be needed. The
761 function that calls the ``mii_ts->txtstamp()`` hook is named
775 discoverable and attachable to a ``struct phy_device`` through Device Tree, and
782 Stacked PHCs, especially DSA (but not only) - since that doesn't require any
784 all possible code paths - is that they uncover bugs which were impossible to
788 skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
791 driver or a MII bus snooping device driver, should set this flag.
799 the ``.ndo_eth_ioctl`` ("``priv->hwtstamp_tx_enabled == true``") and the
800 current skb requires a TX timestamp ("``skb_shinfo(skb)->tx_flags &
802 "``skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS``" flag. Note: as
810 "``skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS``" was set. With a stacked
815 The correct solution for this problem is for MAC drivers to have a compound
817 "``skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS``", but also for
818 "``priv->hwtstamp_tx_enabled == true``". Because the rest of the system ensures