This is a note to let you know that I've just added the patch titled mlxsw: pci: Avoid flow control for EMAD packets to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mlxsw-pci-avoid-flow-control-for-emad-packets.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit b30f356a29a1d307fb857a70d50bfade6540d1bf Author: Danielle Ratson <danieller@xxxxxxxxxx> Date: Wed Jan 5 12:22:27 2022 +0200 mlxsw: pci: Avoid flow control for EMAD packets [ Upstream commit d43e4271747ace01a27a49a97a397cb4219f6487 ] Locally generated packets ingress the device through its CPU port. When the CPU port is congested and there are not enough credits in its headroom buffer, packets can be dropped. While this might be acceptable for data packets that traverse the network, configuration packets exchanged between the host and the device (EMADs) should not be subjected to this flow control. The "sdq_lp" bit in the SDQ (Send Descriptor Queue) context allows the host to instruct the device to treat packets sent on this queue as "local processing" and always process them, regardless of the state of the CPU port's headroom. Add the definition of this bit and set it for the dedicated SDQ reserved for the transmission of EMAD packets. This makes the "local processing" bit in the WQE (Work Queue Element) redundant, so clear it. Signed-off-by: Danielle Ratson <danieller@xxxxxxxxxx> Signed-off-by: Ido Schimmel <idosch@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/ethernet/mellanox/mlxsw/cmd.h b/drivers/net/ethernet/mellanox/mlxsw/cmd.h index 392ce3cb27f72..51b260d54237e 100644 --- a/drivers/net/ethernet/mellanox/mlxsw/cmd.h +++ b/drivers/net/ethernet/mellanox/mlxsw/cmd.h @@ -935,6 +935,18 @@ static inline int mlxsw_cmd_sw2hw_rdq(struct mlxsw_core *mlxsw_core, */ MLXSW_ITEM32(cmd_mbox, sw2hw_dq, cq, 0x00, 24, 8); +enum mlxsw_cmd_mbox_sw2hw_dq_sdq_lp { + MLXSW_CMD_MBOX_SW2HW_DQ_SDQ_LP_WQE, + MLXSW_CMD_MBOX_SW2HW_DQ_SDQ_LP_IGNORE_WQE, +}; + +/* cmd_mbox_sw2hw_dq_sdq_lp + * SDQ local Processing + * 0: local processing by wqe.lp + * 1: local processing (ignoring wqe.lp) + */ +MLXSW_ITEM32(cmd_mbox, sw2hw_dq, sdq_lp, 0x00, 23, 1); + /* cmd_mbox_sw2hw_dq_sdq_tclass * SDQ: CPU Egress TClass * RDQ: Reserved diff --git a/drivers/net/ethernet/mellanox/mlxsw/pci.c b/drivers/net/ethernet/mellanox/mlxsw/pci.c index 01c3235ab2bdf..d9f9cbba62465 100644 --- a/drivers/net/ethernet/mellanox/mlxsw/pci.c +++ b/drivers/net/ethernet/mellanox/mlxsw/pci.c @@ -285,6 +285,7 @@ static int mlxsw_pci_sdq_init(struct mlxsw_pci *mlxsw_pci, char *mbox, struct mlxsw_pci_queue *q) { int tclass; + int lp; int i; int err; @@ -292,9 +293,12 @@ static int mlxsw_pci_sdq_init(struct mlxsw_pci *mlxsw_pci, char *mbox, q->consumer_counter = 0; tclass = q->num == MLXSW_PCI_SDQ_EMAD_INDEX ? MLXSW_PCI_SDQ_EMAD_TC : MLXSW_PCI_SDQ_CTL_TC; + lp = q->num == MLXSW_PCI_SDQ_EMAD_INDEX ? MLXSW_CMD_MBOX_SW2HW_DQ_SDQ_LP_IGNORE_WQE : + MLXSW_CMD_MBOX_SW2HW_DQ_SDQ_LP_WQE; /* Set CQ of same number of this SDQ. */ mlxsw_cmd_mbox_sw2hw_dq_cq_set(mbox, q->num); + mlxsw_cmd_mbox_sw2hw_dq_sdq_lp_set(mbox, lp); mlxsw_cmd_mbox_sw2hw_dq_sdq_tclass_set(mbox, tclass); mlxsw_cmd_mbox_sw2hw_dq_log2_dq_sz_set(mbox, 3); /* 8 pages */ for (i = 0; i < MLXSW_PCI_AQ_PAGES; i++) { @@ -1678,7 +1682,7 @@ static int mlxsw_pci_skb_transmit(void *bus_priv, struct sk_buff *skb, wqe = elem_info->elem; mlxsw_pci_wqe_c_set(wqe, 1); /* always report completion */ - mlxsw_pci_wqe_lp_set(wqe, !!tx_info->is_emad); + mlxsw_pci_wqe_lp_set(wqe, 0); mlxsw_pci_wqe_type_set(wqe, MLXSW_PCI_WQE_TYPE_ETHERNET); err = mlxsw_pci_wqe_frag_map(mlxsw_pci, wqe, 0, skb->data,