From acca79c012342e9f64eef86d3756c6e461adfc6c Mon Sep 17 00:00:00 2001 From: Vinicius Costa Gomes Date: Fri, 30 Mar 2018 17:06:52 -0700 Subject: [PATCH] igb: Fix the transmission mode of queue 0 for Qav mode When Qav mode is enabled, queue 0 should be kept on Stream Reservation mode. From the i210 datasheet, section 8.12.19: "Note: Queue0 QueueMode must be set to 1b when TransmitMode is set to Qav." ("QueueMode 1b" represents the Stream Reservation mode) The solution is to give queue 0 the all the credits it might need, so it has priority over queue 1. A situation where this can happen is when cbs is "installed" only on queue 1, leaving queue 0 alone. For example: $ tc qdisc replace dev enp2s0 handle 100: parent root mqprio num_tc 3 \ map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 queues 1@0 1@1 2@2 hw 0 $ tc qdisc replace dev enp2s0 parent 100:2 cbs locredit -1470 \ hicredit 30 sendslope -980000 idleslope 20000 offload 1 Signed-off-by: Vinicius Costa Gomes Tested-by: Aaron Brown Signed-off-by: Jeff Kirsher --- drivers/net/ethernet/intel/igb/igb_main.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c index c1c0bc30a16d8..cce7ada892551 100644 --- a/drivers/net/ethernet/intel/igb/igb_main.c +++ b/drivers/net/ethernet/intel/igb/igb_main.c @@ -1700,7 +1700,22 @@ static void igb_configure_cbs(struct igb_adapter *adapter, int queue, WARN_ON(hw->mac.type != e1000_i210); WARN_ON(queue < 0 || queue > 1); - if (enable) { + if (enable || queue == 0) { + /* i210 does not allow the queue 0 to be in the Strict + * Priority mode while the Qav mode is enabled, so, + * instead of disabling strict priority mode, we give + * queue 0 the maximum of credits possible. + * + * See section 8.12.19 of the i210 datasheet, "Note: + * Queue0 QueueMode must be set to 1b when + * TransmitMode is set to Qav." + */ + if (queue == 0 && !enable) { + /* max "linkspeed" idleslope in kbps */ + idleslope = 1000000; + hicredit = ETH_FRAME_LEN; + } + set_tx_desc_fetch_prio(hw, queue, TX_QUEUE_PRIO_HIGH); set_queue_mode(hw, queue, QUEUE_MODE_STREAM_RESERVATION); -- 2.39.5