[dpdk-dev] [PATCH 4/6] net/sfc: port HW stats must work if periodic DMA is absent

[Andrew Rybchenko <arybchenko@solarflare.com>]

From: Ivan Malov <ivan.malov@oktetlabs.ru>

If periodic DMA statistics feature is absent (particularly,
while running over VF), the PMD must provide an ability to
cope with it using explicit update requests which are kept
restrained according to 'stats_update_period_ms' parameter

Signed-off-by: Ivan Malov <ivan.malov@oktetlabs.ru>
Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
Reviewed-by: Andy Moreton <amoreton@solarflare.com>
---
 drivers/net/sfc/sfc.h      |  9 +++++++++
 drivers/net/sfc/sfc_port.c | 27 ++++++++++++++++++++++++---
 2 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/drivers/net/sfc/sfc.h b/drivers/net/sfc/sfc.h
index 8e094e0..204a054 100644
--- a/drivers/net/sfc/sfc.h
+++ b/drivers/net/sfc/sfc.h
@@ -155,6 +155,8 @@ struct sfc_port {
 	efsys_mem_t			mac_stats_dma_mem;
 	uint16_t			mac_stats_update_period_ms;
 	uint32_t			mac_stats_update_generation;
+	boolean_t			mac_stats_periodic_dma_supported;
+	uint64_t			mac_stats_last_request_timestamp;
 
 	uint32_t		mac_stats_mask[EFX_MAC_STATS_MASK_NPAGES];
 };
@@ -254,6 +256,13 @@ sfc_adapter_lock_fini(__rte_unused struct sfc_adapter *sa)
 	/* Just for symmetry of the API */
 }
 
+/** Get the number of milliseconds since boot from the default timer */
+static inline uint64_t
+sfc_get_system_msecs(void)
+{
+	return rte_get_timer_cycles() * MS_PER_S / rte_get_timer_hz();
+}
+
 int sfc_dma_alloc(const struct sfc_adapter *sa, const char *name, uint16_t id,
 		  size_t len, int socket_id, efsys_mem_t *esmp);
 void sfc_dma_free(const struct sfc_adapter *sa, efsys_mem_t *esmp);
diff --git a/drivers/net/sfc/sfc_port.c b/drivers/net/sfc/sfc_port.c
index 07a61c4..5a9740c 100644
--- a/drivers/net/sfc/sfc_port.c
+++ b/drivers/net/sfc/sfc_port.c
@@ -67,8 +67,23 @@ sfc_port_update_mac_stats(struct sfc_adapter *sa)
 	if (sa->state != SFC_ADAPTER_STARTED)
 		return EINVAL;
 
-	/* If periodic statistics DMA'ing is off, request explicitly */
-	if (port->mac_stats_update_period_ms == 0) {
+	/*
+	 * If periodic statistics DMA'ing is off or if not supported,
+	 * make a manual request and keep an eye on timer if need be
+	 */
+	if (!port->mac_stats_periodic_dma_supported ||
+	    (port->mac_stats_update_period_ms == 0)) {
+		if (port->mac_stats_update_period_ms != 0) {
+			uint64_t timestamp = sfc_get_system_msecs();
+
+			if ((timestamp -
+			     port->mac_stats_last_request_timestamp) <
+			    port->mac_stats_update_period_ms)
+				return 0;
+
+			port->mac_stats_last_request_timestamp = timestamp;
+		}
+
 		rc = efx_mac_stats_upload(sa->nic, esmp);
 		if (rc != 0)
 			return rc;
@@ -187,8 +202,14 @@ sfc_port_start(struct sfc_adapter *sa)
 		rc = efx_mac_stats_periodic(sa->nic, &port->mac_stats_dma_mem,
 					    port->mac_stats_update_period_ms,
 					    B_FALSE);
-		if (rc != 0)
+		if (rc == 0) {
+			port->mac_stats_periodic_dma_supported = B_TRUE;
+		} else if (rc == EOPNOTSUPP) {
+			port->mac_stats_periodic_dma_supported = B_FALSE;
+			port->mac_stats_last_request_timestamp = 0;
+		} else {
 			goto fail_mac_stats_periodic;
+		}
 	}
 
 	sfc_log_init(sa, "disable MAC drain");
-- 
2.9.3