Hi Jeff, > On Jun 26, 2019, at 12:44 PM, Kirsher, Jeffrey T > <jeffrey.t.kirs...@intel.com> wrote: > > On Tue, 2019-06-25 at 15:07 -0700, Vedang Patel wrote: >> If a packet which is utilizing the launchtime feature (via SO_TXTIME >> socket >> option) also requests the hardware transmit timestamp, the hardware >> timestamp is not delivered to the userspace. This is because the >> value in >> skb->tstamp is mistaken as the software timestamp. >> >> Applications, like ptp4l, request a hardware timestamp by setting the >> SOF_TIMESTAMPING_TX_HARDWARE socket option. Whenever a new timestamp >> is >> detected by the driver (this work is done in igb_ptp_tx_work() which >> calls >> igb_ptp_tx_hwtstamps() in igb_ptp.c[1]), it will queue the timestamp >> in the >> ERR_QUEUE for the userspace to read. When the userspace is ready, it >> will >> issue a recvmsg() call to collect this timestamp. The problem is in >> this >> recvmsg() call. If the skb->tstamp is not cleared out, it will be >> interpreted as a software timestamp and the hardware tx timestamp >> will not >> be successfully sent to the userspace. Look at skb_is_swtx_tstamp() >> and the >> callee function __sock_recv_timestamp() in net/socket.c for more >> details. >> >> Signed-off-by: Vedang Patel <vedang.pa...@intel.com> >> --- >> drivers/net/ethernet/intel/igb/igb_main.c | 1 + >> 1 file changed, 1 insertion(+) > > Since this fix is really not needed for the rest of the patch series, > if you have to do another version of the series, can you drop this > patch from any future version? I don't want to keep spinning my > validation team on a updated version of this patch, that is not really > being updated. > > I plan to take this version of the patch and will hold onto it for my > next 1GbE updates to Dave.
This patch is needed for ptp4l to function properly when txtime-assist mode is enabled. So, dropping this patch will break the series. When are you planning to submit the next set of updates to Dave? If a new version is needed, I can plan to send it out after you send your updates. Thanks, Vedang
