Faizal Rahim <faizal.abdul.ra...@linux.intel.com> writes: > Testing uncovered that even when the taprio gate is closed, some packets > still transmit. > > According to i225/6 hardware errata [1], traffic might overflow the > planned QBV window. This happens because MAC maintains an internal buffer, > primarily for supporting half duplex retries. Therefore, even when the > gate closes, residual MAC data in the buffer may still transmit. > > To mitigate this for i226, reduce the MAC's internal buffer from 192 bytes > to the recommended 88 bytes by modifying the RETX_CTL register value. > > This follows guidelines from: > [1] Ethernet Controller I225/I22 Spec Update Rev 2.1 Errata Item 9: > TSN: Packet Transmission Might Cross Qbv Window > [2] I225/6 SW User Manual Rev 1.2.4: Section 8.11.5 Retry Buffer Control > > Note that the RETX_CTL register can't be used in TSN mode because half > duplex feature cannot coexist with TSN. > > Test Steps: > 1. Send taprio cmd to board A: > tc qdisc replace dev enp1s0 parent root handle 100 taprio \ > num_tc 4 \ > map 3 2 1 0 3 3 3 3 3 3 3 3 3 3 3 3 \ > queues 1@0 1@1 1@2 1@3 \ > base-time 0 \ > sched-entry S 0x07 500000 \ > sched-entry S 0x0f 500000 \ > flags 0x2 \ > txtime-delay 0 > > Note that for TC3, gate should open for 500us and close for another > 500us. > > 3. Take tcpdump log on Board B. > > 4. Send udp packets via UDP tai app from Board A to Board B. > > 5. Analyze tcpdump log via wireshark log on Board B. Ensure that the > total time from the first to the last packet received during one cycle > for TC3 does not exceed 500us. > > Signed-off-by: Faizal Rahim <faizal.abdul.ra...@linux.intel.com> > --- > v1: > https://patchwork.kernel.org/project/netdevbpf/patch/20240701100058.3301229-1-faizal.abdul.ra...@linux.intel.com/ > > Changelog: > v1 -> v2 > - Update commit description (Paul). > - Rename qbvfullth -> qbvfullthreshold (Paul). > ---
Looks fine. Acked-by: Vinicius Costa Gomes <vinicius.go...@intel.com> Cheers, -- Vinicius
