[PATCH net v2 5/5] net: mvneta: keep the TX rate limits across open and MTU change

[Josef Schlehofer <pepe.schlehofer@gmail.com>]

After the interface is brought up again or its MTU is changed, every
per-queue rate limit set by mqprio runs at 10.23 Mbit/s, whatever rate
was configured. tc still shows the configured rates.

mvneta_txq_hw_init() writes the token configuration of the legacy rate
limiter for each TX queue. This also sets the refill value of the
queue's token bucket to 1023, which is 10.23 Mbit/s at the refill
period that mqprio uses.

Remember the refill of each rate limited queue and program the rate
limits again when the port is started. Resume also starts the port
with mvneta_start_dev().

Tested on a Turris Omnia (Armada 385) with 1 Mbit/s limits on a
100 Mbit/s link. After the link was set down and up, or the MTU was
changed, each busy TX queue carried about 10 Mbit/s. With this patch it
stays at about 1 Mbit/s.

Fixes: 2551dc9e398c ("net: mvneta: Add TC traffic shaping offload")
Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>
---
 drivers/net/ethernet/marvell/mvneta.c | 29 ++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index d3a6bf8f383e..92a2ea930002 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -686,6 +686,9 @@ struct mvneta_tx_queue {
 
 	u32 done_pkts_coal;
 
+	/* Bucket refill of the mqprio rate limit, 0 when not limited */
+	u32 bucket_refill;
+
 	/* Virtual address of the TX DMA descriptors array */
 	struct mvneta_tx_desc *descs;
 
@@ -3773,6 +3776,8 @@ static int mvneta_config_interface(struct mvneta_port *pp,
 	return ret;
 }
 
+static void mvneta_restore_per_queue_rate_limit(struct mvneta_port *pp);
+
 static void mvneta_start_dev(struct mvneta_port *pp)
 {
 	int cpu;
@@ -3782,6 +3787,7 @@ static void mvneta_start_dev(struct mvneta_port *pp)
 	mvneta_max_rx_size_set(pp, pp->pkt_size);
 	mvneta_txq_max_tx_size_set(pp, pp->pkt_size);
 	mvneta_txq_wrr_set(pp, pp->pkt_size);
+	mvneta_restore_per_queue_rate_limit(pp);
 
 	/* start the Rx/Tx activity */
 	mvneta_port_enable(pp);
@@ -5234,8 +5240,10 @@ static void mvneta_disable_per_queue_rate_limit(struct mvneta_port *pp)
 	/* The token buckets still limit the queues, refill them at full rate */
 	val = (1 << MVNETA_TXQ_BUCKET_REFILL_PERIOD_SHIFT) |
 	      MVNETA_TXQ_BUCKET_REFILL_VALUE_MAX;
-	for (queue = 0; queue < txq_number; queue++)
+	for (queue = 0; queue < txq_number; queue++) {
+		pp->txqs[queue].bucket_refill = 0;
 		mvreg_write(pp, MVNETA_TXQ_BUCKET_REFILL_REG(queue), val);
+	}
 }
 
 static int mvneta_setup_queue_rates(struct mvneta_port *pp, int queue,
@@ -5261,11 +5269,30 @@ static int mvneta_setup_queue_rates(struct mvneta_port *pp, int queue,
 	val |= (MVNETA_TXQ_BUCKET_REFILL_PERIOD <<
 		MVNETA_TXQ_BUCKET_REFILL_PERIOD_SHIFT);
 
+	pp->txqs[queue].bucket_refill = val;
 	mvreg_write(pp, MVNETA_TXQ_BUCKET_REFILL_REG(queue), val);
 
 	return 0;
 }
 
+/* The TX queue setup overwrites the rate limits, program them again */
+static void mvneta_restore_per_queue_rate_limit(struct mvneta_port *pp)
+{
+	int queue;
+
+	for (queue = 0; queue < txq_number; queue++)
+		if (pp->txqs[queue].bucket_refill)
+			break;
+
+	if (queue == txq_number || mvneta_enable_per_queue_rate_limit(pp))
+		return;
+
+	for (; queue < txq_number; queue++)
+		if (pp->txqs[queue].bucket_refill)
+			mvreg_write(pp, MVNETA_TXQ_BUCKET_REFILL_REG(queue),
+				    pp->txqs[queue].bucket_refill);
+}
+
 static int mvneta_setup_mqprio(struct net_device *dev,
 			       struct tc_mqprio_qopt_offload *mqprio)
 {
-- 
2.54.0 (Apple Git-157)