diff options
Diffstat (limited to 'drivers/net/ethernet/sfc/nic.h')
| -rw-r--r-- | drivers/net/ethernet/sfc/nic.h | 29 |
1 files changed, 24 insertions, 5 deletions
diff --git a/drivers/net/ethernet/sfc/nic.h b/drivers/net/ethernet/sfc/nic.h index 60f85149fc4c..f77cce034ad4 100644 --- a/drivers/net/ethernet/sfc/nic.h +++ b/drivers/net/ethernet/sfc/nic.h @@ -71,9 +71,17 @@ efx_tx_desc(struct efx_tx_queue *tx_queue, unsigned int index) return ((efx_qword_t *) (tx_queue->txd.buf.addr)) + index; } -/* Report whether the NIC considers this TX queue empty, given the - * write_count used for the last doorbell push. May return false - * negative. +/* Get partner of a TX queue, seen as part of the same net core queue */ +static struct efx_tx_queue *efx_tx_queue_partner(struct efx_tx_queue *tx_queue) +{ + if (tx_queue->queue & EFX_TXQ_TYPE_OFFLOAD) + return tx_queue - EFX_TXQ_TYPE_OFFLOAD; + else + return tx_queue + EFX_TXQ_TYPE_OFFLOAD; +} + +/* Report whether this TX queue would be empty for the given write_count. + * May return false negative. */ static inline bool __efx_nic_tx_is_empty(struct efx_tx_queue *tx_queue, unsigned int write_count) @@ -86,9 +94,18 @@ static inline bool __efx_nic_tx_is_empty(struct efx_tx_queue *tx_queue, return ((empty_read_count ^ write_count) & ~EFX_EMPTY_COUNT_VALID) == 0; } -static inline bool efx_nic_tx_is_empty(struct efx_tx_queue *tx_queue) +/* Decide whether we can use TX PIO, ie. write packet data directly into + * a buffer on the device. This can reduce latency at the expense of + * throughput, so we only do this if both hardware and software TX rings + * are empty. This also ensures that only one packet at a time can be + * using the PIO buffer. + */ +static inline bool efx_nic_may_tx_pio(struct efx_tx_queue *tx_queue) { - return __efx_nic_tx_is_empty(tx_queue, tx_queue->write_count); + struct efx_tx_queue *partner = efx_tx_queue_partner(tx_queue); + return tx_queue->piobuf && + __efx_nic_tx_is_empty(tx_queue, tx_queue->insert_count) && + __efx_nic_tx_is_empty(partner, partner->insert_count); } /* Decide whether to push a TX descriptor to the NIC vs merely writing @@ -96,6 +113,8 @@ static inline bool efx_nic_tx_is_empty(struct efx_tx_queue *tx_queue) * descriptor to an empty queue, but is otherwise pointless. Further, * Falcon and Siena have hardware bugs (SF bug 33851) that may be * triggered if we don't check this. + * We use the write_count used for the last doorbell push, to get the + * NIC's view of the tx queue. */ static inline bool efx_nic_may_push_tx_desc(struct efx_tx_queue *tx_queue, unsigned int write_count) |