Re: [PATCH net-next v8 06/11] net: ti: prueth: Adds HW timestamping support for PTP using PRU-ICSS IEP module
From: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Date: 2025-06-11 10:29:54
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linux-arm-kernel, linux-devicetree, lkml
On 10/06/2025 13:32, Parvathi Pudi wrote:
From: Roger Quadros <redacted> PRU-ICSS IEP module, which is capable of timestamping RX and TX packets at HW level, is used for time synchronization by PTP4L. This change includes interaction between firmware and user space application (ptp4l) with required packet timestamps. The driver initializes the PRU firmware with appropriate mode and configuration flags. Firmware updates local registers with the flags set by driver and uses for further operation. RX SOF timestamp comes along with packet and firmware will rise interrupt with TX SOF timestamp after pushing the packet on to the wire. IEP driver is available in upstream and we are reusing for hardware configuration for ICSSM as well. On top of that we have extended it with the changes for AM57xx SoC. Extended ethtool for reading HW timestamping capability of the PRU interfaces. Currently ordinary clock (OC) configuration has been validated with Linux ptp4l. Signed-off-by: Roger Quadros <redacted> Signed-off-by: Andrew F. Davis <redacted> Signed-off-by: Basharath Hussain Khaja <redacted> Signed-off-by: Parvathi Pudi <parvathi@couthit.com> --- drivers/net/ethernet/ti/icssg/icss_iep.c | 42 ++ drivers/net/ethernet/ti/icssm/icssm_ethtool.c | 23 + drivers/net/ethernet/ti/icssm/icssm_prueth.c | 443 +++++++++++++++++- drivers/net/ethernet/ti/icssm/icssm_prueth.h | 11 + .../net/ethernet/ti/icssm/icssm_prueth_ptp.h | 85 ++++ 5 files changed, 602 insertions(+), 2 deletions(-) create mode 100644 drivers/net/ethernet/ti/icssm/icssm_prueth_ptp.h
[...]
quoted hunk ↗ jump to hunk
@@ -732,9 +949,22 @@ int icssm_emac_rx_packet(struct prueth_emac *emac, u16 *bd_rd_ptr, src_addr += actual_pkt_len; } + if (pkt_info->timestamp) { + src_addr = (void *)PTR_ALIGN((uintptr_t)src_addr, + ICSS_BLOCK_SIZE); + dst_addr = &ts; + memcpy(dst_addr, src_addr, sizeof(ts)); + } + if (!pkt_info->sv_frame) { skb_put(skb, actual_pkt_len); + if (icssm_prueth_ptp_rx_ts_is_enabled(emac) && + pkt_info->timestamp) { + ssh = skb_hwtstamps(skb); + memset(ssh, 0, sizeof(*ssh)); + ssh->hwtstamp = ns_to_ktime(ts); + } /* send packet up the stack */ skb->protocol = eth_type_trans(skb, ndev); netif_receive_skb(skb);
Could you please explain why do you need to copy timestamp to a
temporary variable if you won't use it in some cases? I believe these
2 blocks should be placed under the last if condition and simplified a
bit, like
+ if (icssm_prueth_ptp_rx_ts_is_enabled(emac) &&
+ pkt_info->timestamp) {
+ src_addr = (void*)PTR_ALIGN((uintptr_t)src_addr,
+ ICSS_BLOCK_SIZE);
+ memcpy(&ts, src_addr, sizeof(ts));
+ ssh = skb_hwtstamps(skb);
+ ssh->hwtstamp = ns_to_ktime(ts);
+ }
This will avoid useless copy when the packet will be dropped anyway, WDYT?