Song Yoong Siang wrote:
> This patch adds support to per-packet Tx hardware timestamp request to
> AF_XDP zero-copy packet via XDP Tx metadata framework. Please note that
> user needs to enable Tx HW timestamp capability via igc_ioctl() with
> SIOCSHWTSTAMP cmd before sending xsk Tx hardware timestamp request.
>
> Same as implementation in RX timestamp XDP hints kfunc metadata, Timer 0
> (adjustable clock) is used in xsk Tx hardware timestamp. i225/i226 have
> four sets of timestamping registers. Both *skb and *xsk_tx_buffer pointers
> are used to indicate whether the timestamping register is already occupied.
>
> Furthermore, a boolean variable named xsk_pending_ts is used to hold the
> transmit completion until the tx hardware timestamp is ready. This is
> because, for i225/i226, the timestamp notification event comes some time
> after the transmit completion event. The driver will retrigger hardware irq
> to clean the packet after retrieve the tx hardware timestamp.
>
> Besides, xsk_meta is added into struct igc_tx_timestamp_request as a hook
> to the metadata location of the transmit packet. When the Tx timestamp
> interrupt is fired, the interrupt handler will copy the value of Tx hwts
> into metadata location via xsk_tx_metadata_complete().
>
> Co-developed-by: Lai Peter Jun Ann <jun.ann.lai@xxxxxxxxx>
> Signed-off-by: Lai Peter Jun Ann <jun.ann.lai@xxxxxxxxx>
> Signed-off-by: Song Yoong Siang <yoong.siang.song@xxxxxxxxx>
> ---
[...]
>
> +static void igc_xsk_request_timestamp(void *_priv)
> +{
> + struct igc_metadata_request *meta_req = _priv;
> + struct igc_ring *tx_ring = meta_req->tx_ring;
> + struct igc_tx_timestamp_request *tstamp;
> + u32 tx_flags = IGC_TX_FLAGS_TSTAMP;
> + struct igc_adapter *adapter;
> + unsigned long lock_flags;
> + bool found = false;
> + int i;
> +
> + if (test_bit(IGC_RING_FLAG_TX_HWTSTAMP, &tx_ring->flags)) {
> + adapter = netdev_priv(tx_ring->netdev);
> +
> + spin_lock_irqsave(&adapter->ptp_tx_lock, lock_flags);
> +
> + /* Search for available tstamp regs */
> + for (i = 0; i < IGC_MAX_TX_TSTAMP_REGS; i++) {
> + tstamp = &adapter->tx_tstamp[i];
> +
> + if (tstamp->skb)
> + continue;
> +
> + found = true;
> + break;
Not how I would have written this loop construct seems a bit odd
to default break but it works.
> + }
> +
> + /* Return if no available tstamp regs */
> + if (!found) {
> + adapter->tx_hwtstamp_skipped++;
> + spin_unlock_irqrestore(&adapter->ptp_tx_lock,
> + lock_flags);
> + return;
> + }
[...]
>
> +static void igc_ptp_free_tx_buffer(struct igc_adapter *adapter,
> + struct igc_tx_timestamp_request *tstamp)
> +{
> + if (tstamp->buffer_type == IGC_TX_BUFFER_TYPE_XSK) {
> + /* Release the transmit completion */
> + tstamp->xsk_tx_buffer->xsk_pending_ts = false;
> + tstamp->xsk_tx_buffer = NULL;
> + tstamp->buffer_type = 0;
> +
> + /* Trigger txrx interrupt for transmit completion */
> + igc_xsk_wakeup(adapter->netdev, tstamp->xsk_queue_index, 0);
Just curious because I didn't find it. Fairly sure I just need to look more,
but don't you want to still 'tstamp->skb = NULL' in this path somewhere?
It looks like triggering the tx interrupt again with buffer_type == 0 wouldn't
do the null.
I suspect I just missed it.
