Re: [PATCH v2 14/17] octeontx2-pf: Add basic ethtool support

On Tue, Jan 14, 2020 at 12:32:17PM +0530, sunil.kovvuri@gmail.com wrote:

From: Christina Jacob <redacted>

This patch adds ethtool support for
 - Driver stats, Tx/Rx perqueue and CGX LMAC stats
 - Set/show Rx/Tx queue count
 - Set/show Rx/Tx ring sizes
 - Set/show IRQ coalescing parameters

Signed-off-by: Christina Jacob <redacted>
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
---

[...]

+static void otx2_dev_open(struct net_device *netdev)
+{
+	otx2_open(netdev);
+}
+
+static void otx2_dev_stop(struct net_device *netdev)
+{
+	otx2_stop(netdev);
+}

Why don't you call these directly?

[...]

+/* Get no of queues device supports and current queue count */
+static void otx2_get_channels(struct net_device *dev,
+			      struct ethtool_channels *channel)
+{
+	struct otx2_nic *pfvf = netdev_priv(dev);
+
+	memset(channel, 0, sizeof(*channel));

The structure is already zero initialized in ethtool_get_channels()
(except for cmd).

+	channel->max_rx = pfvf->hw.max_queues;
+	channel->max_tx = pfvf->hw.max_queues;
+
+	channel->rx_count = pfvf->hw.rx_queues;
+	channel->tx_count = pfvf->hw.tx_queues;
+}
+
+/* Set no of Tx, Rx queues to be used */
+static int otx2_set_channels(struct net_device *dev,
+			     struct ethtool_channels *channel)
+{
+	struct otx2_nic *pfvf = netdev_priv(dev);
+	bool if_up = netif_running(dev);
+	int err = 0;
+
+	if (!channel->rx_count || !channel->tx_count)
+		return -EINVAL;
+	if (channel->rx_count > pfvf->hw.max_queues)
+		return -EINVAL;
+	if (channel->tx_count > pfvf->hw.max_queues)
+		return -EINVAL;

The upper bounds are checked in ethtool_set_channels() so that you don't
get here if requested counts are too high.

+
+	if (if_up)
+		otx2_dev_stop(dev);
+
+	pfvf->hw.rx_queues = channel->rx_count;
+	pfvf->hw.tx_queues = channel->tx_count;
+	err = otx2_set_real_num_queues(dev, pfvf->hw.tx_queues,
+				       pfvf->hw.rx_queues);
+	pfvf->qset.cq_cnt = pfvf->hw.tx_queues +  pfvf->hw.rx_queues;
+	if (err)
+		return err;
+
+	if (if_up)
+		otx2_dev_open(dev);

Is it intentional that you leave the device down when the change fails?

+	netdev_info(dev, "Setting num Tx rings to %d, Rx rings to %d success\n",
+		    pfvf->hw.tx_queues, pfvf->hw.rx_queues);
+
+	return err;
+}
+
+static void otx2_get_ringparam(struct net_device *netdev,
+			       struct ethtool_ringparam *ring)
+{
+	struct otx2_nic *pfvf = netdev_priv(netdev);
+	struct otx2_qset *qs = &pfvf->qset;
+
+	ring->rx_max_pending = Q_COUNT(Q_SIZE_MAX);
+	ring->rx_pending = qs->rqe_cnt ? qs->rqe_cnt : Q_COUNT(Q_SIZE_256);
+	ring->tx_max_pending = Q_COUNT(Q_SIZE_MAX);
+	ring->tx_pending = qs->sqe_cnt ? qs->sqe_cnt : Q_COUNT(Q_SIZE_4K);
+}
+
+static int otx2_set_ringparam(struct net_device *netdev,
+			      struct ethtool_ringparam *ring)
+{
+	struct otx2_nic *pfvf = netdev_priv(netdev);
+	bool if_up = netif_running(netdev);
+	struct otx2_qset *qs = &pfvf->qset;
+	u32 rx_count, tx_count;
+
+	if (ring->rx_mini_pending || ring->rx_jumbo_pending)
+		return -EINVAL;
+
+	/* Permitted lengths are 16 64 256 1K 4K 16K 64K 256K 1M  */
+	rx_count = clamp_t(u32, ring->rx_pending,
+			   Q_COUNT(Q_SIZE_MIN), Q_COUNT(Q_SIZE_MAX));

The upper bound is checked in ethtool_set_ringparam().

Michal Kubecek

+	/* On some silicon variants a skid or reserved CQEs are
+	 * needed to avoid CQ overflow.
+	 */
+	if (rx_count < pfvf->hw.rq_skid)
+		rx_count =  pfvf->hw.rq_skid;
+	rx_count = Q_COUNT(Q_SIZE(rx_count, 3));
+
+	/* Due pipelining impact minimum 2000 unused SQ CQE's
+	 * need to maintain to avoid CQ overflow, hence the
+	 * minimum 4K size.
+	 */
+	tx_count = clamp_t(u32, ring->tx_pending,
+			   Q_COUNT(Q_SIZE_4K), Q_COUNT(Q_SIZE_MAX));
+	tx_count = Q_COUNT(Q_SIZE(tx_count, 3));
+
+	if (tx_count == qs->sqe_cnt && rx_count == qs->rqe_cnt)
+		return 0;
+
+	if (if_up)
+		otx2_dev_stop(netdev);
+
+	/* Assigned to the nearest possible exponent. */
+	qs->sqe_cnt = tx_count;
+	qs->rqe_cnt = rx_count;
+
+	if (if_up)
+		otx2_dev_open(netdev);
+	return 0;
+}