On 06/07/2024 18:38, Faizal Rahim wrote:
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> Acked-by: Vinicius Costa Gomes <vinicius.go...@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). --- drivers/net/ethernet/intel/igc/igc_defines.h | 6 ++++ drivers/net/ethernet/intel/igc/igc_tsn.c | 34 ++++++++++++++++++++ 2 files changed, 40 insertions(+)
Tested-by: Mor Bar-Gabay <morx.bar.ga...@intel.com>
