Re: [PATCH net-next v2 3/4] net: macb: Add MQPRIO qdisc hardware offload support
From: Théo Lebrun <theo.lebrun@bootlin.com>
Date: 2026-09-17 09:22:24
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Hello Vineeth, On Wed Sep 9, 2026 at 4:20 PM CEST, Vineeth Karumanchi wrote:
quoted hunk ↗ jump to hunk
Add support for TC_SETUP_QDISC_MQPRIO hardware offload, allowing traffic class to queue mapping via the mqprio qdisc. Implement macb_setup_mqprio() which configures TC-to-queue mappings through netdev_set_num_tc() and netdev_set_tc_queue(), and resets them when num_tc is zero. The driver advertises TC_MQPRIO_HW_OFFLOAD_TCS offload level. Add macb_tc_query_caps() to report mqprio capabilities. Setting validate_queue_counts to true delegates queue count and overlap validation to the mqprio core via mqprio_validate_queue_counts(), avoiding redundant checks in the driver. Signed-off-by: Vineeth Karumanchi <redacted> --- Changes in v2: - No functional change; rebased on net-next, which renamed the struct net_device pointer to "netdev" (was "dev"/"ndev"). drivers/net/ethernet/cadence/macb_main.c | 59 ++++++++++++++++++++++++ 1 file changed, 59 insertions(+)diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c index ff7e02d3fab8..67150ff03066 100644 --- a/drivers/net/ethernet/cadence/macb_main.c +++ b/drivers/net/ethernet/cadence/macb_main.c@@ -4492,6 +4492,60 @@ static int macb_setup_taprio(struct net_device *netdev, return err; } +static int macb_setup_mqprio(struct net_device *netdev, + struct tc_mqprio_qopt_offload *mqprio) +{ + struct tc_mqprio_qopt *qopt = &mqprio->qopt; + u8 num_tc = qopt->num_tc; + int err; + u8 i; + + /* Handle reset case early */ + if (!num_tc) { + netdev_reset_tc(netdev); + return 0; + } + + /* Configure traffic classes */ + qopt->hw = TC_MQPRIO_HW_OFFLOAD_TCS; + + err = netdev_set_num_tc(netdev, num_tc); + if (err) + return err; + + for (i = 0; i < num_tc; i++) { + err = netdev_set_tc_queue(netdev, i, qopt->count[i], + qopt->offset[i]); + if (err) + goto err_reset_tc; + + netdev_dbg(netdev, "MQPRIO: TC%d -> queue %u (count=%u)\n", + i, qopt->offset[i], qopt->count[i]); + }
MACB queue N is always higher priority than queue M if N > M. Here we should refuse the setup if mqprio->qopt->offset[i] isn't sorted no? I asked an LLM and it found a precedent in igc: igc_tsn_is_tc_to_queue_priority_ordered() https://elixir.bootlin.com/linux/v7.2.5/source/drivers/net/ethernet/intel/igc/igc_main.c#L6797-L6801
+ + return 0; + +err_reset_tc: + netdev_reset_tc(netdev); + return err; +}
Thanks, -- Théo Lebrun, Bootlin Embedded Linux and Kernel engineering https://bootlin.com