4.16-stable review patch. If anyone has any objections, please let me know.
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From: Vinicius Costa Gomes vinicius.gomes@intel.com
[ Upstream commit 2707df9773cd2cb8b0f35b8592431b301da9d352 ]
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 vinicius.gomes@intel.com Tested-by: Aaron Brown aaron.f.brown@intel.com Signed-off-by: Jeff Kirsher jeffrey.t.kirsher@intel.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/ethernet/intel/igb/igb_main.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-)
--- a/drivers/net/ethernet/intel/igb/igb_main.c +++ b/drivers/net/ethernet/intel/igb/igb_main.c @@ -1698,7 +1698,22 @@ static void igb_configure_cbs(struct igb 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);