sfc: Add TX queues for high-priority traffic

Implement the ndo_setup_tc() operation with 2 traffic classes.

Current Solarstorm controllers do not implement TX queue priority, but
they do allow queues to be 'paced' with an enforced delay between
packets.  Paced and unpaced queues are scheduled in round-robin within
two separate hardware bins (paced queues with a large delay may be
placed into a third bin temporarily, but we won't use that).  If there
are queues in both bins, the TX scheduler will alternate between them.

If we make high-priority queues unpaced and best-effort queues paced,
and high-priority queues are mostly empty, a single high-priority queue
can then instantly take 50% of the packet rate regardless of how many
of the best-effort queues have descriptors outstanding.

We do not actually want an enforced delay between packets on best-
effort queues, so we set the pace value to a reserved value that
actually results in a delay of 0.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

1 files changed, 38 insertions, 13 deletions

diff --git a/drivers/net/sfc/nic.c b/drivers/net/sfc/nic.c
index da386599ab6..1d0b8b6f25c 100644
--- a/drivers/net/sfc/nic.c
+++ b/drivers/net/sfc/nic.c
@@ -445,8 +445,8 @@ int efx_nic_probe_tx(struct efx_tx_queue *tx_queue)
 
 void efx_nic_init_tx(struct efx_tx_queue *tx_queue)
 {
-        efx_oword_t tx_desc_ptr;
         struct efx_nic *efx = tx_queue->efx;
+        efx_oword_t reg;
 
         tx_queue->flushed = FLUSH_NONE;
 
@@ -454,7 +454,7 @@ void efx_nic_init_tx(struct efx_tx_queue *tx_queue)
         efx_init_special_buffer(efx, &tx_queue->txd);
 
         /* Push TX descriptor ring to card */
-        EFX_POPULATE_OWORD_10(tx_desc_ptr,
+        EFX_POPULATE_OWORD_10(reg,
                               FRF_AZ_TX_DESCQ_EN, 1,
                               FRF_AZ_TX_ISCSI_DDIG_EN, 0,
                               FRF_AZ_TX_ISCSI_HDIG_EN, 0,
@@ -470,17 +470,15 @@ void efx_nic_init_tx(struct efx_tx_queue *tx_queue)
 
         if (efx_nic_rev(efx) >= EFX_REV_FALCON_B0) {
                 int csum = tx_queue->queue & EFX_TXQ_TYPE_OFFLOAD;
-                EFX_SET_OWORD_FIELD(tx_desc_ptr, FRF_BZ_TX_IP_CHKSM_DIS, !csum);
-                EFX_SET_OWORD_FIELD(tx_desc_ptr, FRF_BZ_TX_TCP_CHKSM_DIS,
+                EFX_SET_OWORD_FIELD(reg, FRF_BZ_TX_IP_CHKSM_DIS, !csum);
+                EFX_SET_OWORD_FIELD(reg, FRF_BZ_TX_TCP_CHKSM_DIS,
                                     !csum);
         }
 
-        efx_writeo_table(efx, &tx_desc_ptr, efx->type->txd_ptr_tbl_base,
+        efx_writeo_table(efx, &reg, efx->type->txd_ptr_tbl_base,
                          tx_queue->queue);
 
         if (efx_nic_rev(efx) < EFX_REV_FALCON_B0) {
-                efx_oword_t reg;
-
                 /* Only 128 bits in this register */
                 BUILD_BUG_ON(EFX_MAX_TX_QUEUES > 128);
 
@@ -491,6 +489,16 @@ void efx_nic_init_tx(struct efx_tx_queue *tx_queue)
                         set_bit_le(tx_queue->queue, (void *)&reg);
                 efx_writeo(efx, &reg, FR_AA_TX_CHKSM_CFG);
         }
+
+        if (efx_nic_rev(efx) >= EFX_REV_FALCON_B0) {
+                EFX_POPULATE_OWORD_1(reg,
+                                     FRF_BZ_TX_PACE,
+                                     (tx_queue->queue & EFX_TXQ_TYPE_HIGHPRI) ?
+                                     FFE_BZ_TX_PACE_OFF :
+                                     FFE_BZ_TX_PACE_RESERVED);
+                efx_writeo_table(efx, &reg, FR_BZ_TX_PACE_TBL,
+                                 tx_queue->queue);
+        }
 }
 
 static void efx_flush_tx_queue(struct efx_tx_queue *tx_queue)
@@ -1238,8 +1246,10 @@ int efx_nic_flush_queues(struct efx_nic *efx)
 
         /* Flush all tx queues in parallel */
         efx_for_each_channel(channel, efx) {
-                efx_for_each_channel_tx_queue(tx_queue, channel)
-                        efx_flush_tx_queue(tx_queue);
+                efx_for_each_possible_channel_tx_queue(tx_queue, channel) {
+                        if (tx_queue->initialised)
+                                efx_flush_tx_queue(tx_queue);
+                }
         }
 
         /* The hardware supports four concurrent rx flushes, each of which may
@@ -1262,8 +1272,9 @@ int efx_nic_flush_queues(struct efx_nic *efx)
                                         ++rx_pending;
                                 }
                         }
-                        efx_for_each_channel_tx_queue(tx_queue, channel) {
-                                if (tx_queue->flushed != FLUSH_DONE)
+                        efx_for_each_possible_channel_tx_queue(tx_queue, channel) {
+                                if (tx_queue->initialised &&
+                                    tx_queue->flushed != FLUSH_DONE)
                                         ++tx_pending;
                         }
                 }
@@ -1278,8 +1289,9 @@ int efx_nic_flush_queues(struct efx_nic *efx)
         /* Mark the queues as all flushed. We're going to return failure
          * leading to a reset, or fake up success anyway */
         efx_for_each_channel(channel, efx) {
-                efx_for_each_channel_tx_queue(tx_queue, channel) {
-                        if (tx_queue->flushed != FLUSH_DONE)
+                efx_for_each_possible_channel_tx_queue(tx_queue, channel) {
+                        if (tx_queue->initialised &&
+                            tx_queue->flushed != FLUSH_DONE)
                                 netif_err(efx, hw, efx->net_dev,
                                           "tx queue %d flush command timed out\n",
                                           tx_queue->queue);
@@ -1682,6 +1694,19 @@ void efx_nic_init_common(struct efx_nic *efx)
         if (efx_nic_rev(efx) >= EFX_REV_FALCON_B0)
                 EFX_SET_OWORD_FIELD(temp, FRF_BZ_TX_FLUSH_MIN_LEN_EN, 1);
         efx_writeo(efx, &temp, FR_AZ_TX_RESERVED);
+
+        if (efx_nic_rev(efx) >= EFX_REV_FALCON_B0) {
+                EFX_POPULATE_OWORD_4(temp,
+                                     /* Default values */
+                                     FRF_BZ_TX_PACE_SB_NOT_AF, 0x15,
+                                     FRF_BZ_TX_PACE_SB_AF, 0xb,
+                                     FRF_BZ_TX_PACE_FB_BASE, 0,
+                                     /* Allow large pace values in the
+                                      * fast bin. */
+                                     FRF_BZ_TX_PACE_BIN_TH,
+                                     FFE_BZ_TX_PACE_RESERVED);
+                efx_writeo(efx, &temp, FR_BZ_TX_PACE);
+        }
 }
 
 /* Register dump */