Subject: Re: [PATCH 4/4] net: ethernet: ti: cpsw: add ethtool channels support

From: Grygorii Strashko <[email-masked]>
Date: Fri, 8 Jul 2016 16:33:09 +0300

On 06/30/2016 10:04 PM, Ivan Khoronzhuk wrote:
> These ops allow to control number of channels driver is allowed to
> work with. The maximum number of channels is 8 for rx and 8 for tx.
> After this patch the following commands are possible:
> 
> $ ethtool -l eth0
> $ ethtool -L eth0 rx 6 tx 6

Could you add some description here about switch vs dual_mac behavior? 

> 
> Signed-off-by: Ivan Khoronzhuk <[email-masked]>
> ---
>   drivers/net/ethernet/ti/cpsw.c | 188 +++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 188 insertions(+)
> 
> diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
> index 595ed56..729b8be 100644
> --- a/drivers/net/ethernet/ti/cpsw.c
> +++ b/drivers/net/ethernet/ti/cpsw.c
> @@ -740,6 +740,11 @@ static void cpsw_rx_handler(void *token, int len, int status)
>   	}
>   
>   requeue:
> +	if (netif_dormant(ndev)) {
> +		dev_kfree_skb_any(new_skb);
> +		return;
> +	}
> +
>   	ch = priv->rxch[skb_get_queue_mapping(new_skb)];
>   	ret = cpdma_chan_submit(ch, new_skb, new_skb->data,
>   				skb_tailroom(new_skb), 0);
> @@ -2077,6 +2082,187 @@ static void cpsw_ethtool_op_complete(struct net_device *ndev)
>   		cpsw_err(priv, drv, "ethtool complete failed %d\n", ret);
>   }
>   
> +static void cpsw_get_channels(struct net_device *dev,
> +			      struct ethtool_channels *ch)
> +{
> +	struct cpsw_priv *priv = netdev_priv(dev);
> +
> +	ch->max_combined = 0;
> +	ch->max_rx = CPSW_MAX_QUEUES;
> +	ch->max_tx = CPSW_MAX_QUEUES;
> +	ch->max_other = 0;
> +	ch->other_count = 0;
> +	ch->rx_count = priv->rx_ch_num;
> +	ch->tx_count = priv->tx_ch_num;
> +	ch->combined_count = 0;
> +}
> +
> +static int cpsw_check_ch_settings(struct cpsw_priv *priv,
> +				  struct ethtool_channels *ch)
> +{
> +	if (ch->combined_count)
> +		return -EINVAL;
> +
> +	/* verify we have at least one channel in each direction */
> +	if (!ch->rx_count || !ch->tx_count)
> +		return -EINVAL;
> +
> +	if (ch->rx_count > priv->data.channels ||
> +	    ch->tx_count > priv->data.channels)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static void cpsw_sync_dual_ch_list(struct net_device *sdev,
> +				   struct net_device *ddev)
> +{
> +	struct cpsw_priv *priv_s, *priv_d;
> +	int i;
> +
> +	priv_s = netdev_priv(sdev);
> +	priv_d = netdev_priv(ddev);
> +
> +	priv_d->rx_ch_num = priv_s->rx_ch_num;
> +	priv_d->tx_ch_num = priv_s->tx_ch_num;
> +
> +	for (i = 0; i < priv_d->tx_ch_num; i++)
> +		priv_d->txch[i] = priv_s->txch[i];
> +	for (i = 0; i < priv_d->rx_ch_num; i++)
> +		priv_d->rxch[i] = priv_s->rxch[i];
> +}
> +
> +static int cpsw_update_channels_res(struct cpsw_priv *priv, int ch_num, int rx)
> +{
> +	int (*poll)(struct napi_struct *, int);
> +	void (*handler)(void *, int, int);
> +	struct cpdma_chan **chan;
> +	int *ch;
> +	int ret;
> +
> +	if (rx) {
> +		ch = &priv->rx_ch_num;
> +		chan = priv->rxch;
> +		handler = cpsw_rx_handler;
> +		poll = cpsw_rx_poll;
> +	} else {
> +		ch = &priv->tx_ch_num;
> +		chan = priv->txch;
> +		handler = cpsw_tx_handler;
> +		poll = cpsw_tx_poll;
> +	}
> +
> +	while (*ch < ch_num) {
> +		chan[*ch] = cpdma_chan_create(priv->dma, *ch, handler, rx);
> +
> +		if (IS_ERR(chan[*ch]))
> +			return PTR_ERR(chan[*ch]);
> +
> +		if (!chan[*ch])
> +			return -EINVAL;
> +
> +		dev_info(priv->dev, "created new %d %s channel\n", *ch,
> +			 (rx ? "rx" : "tx"));
> +		(*ch)++;
> +	}
> +
> +	while (*ch > ch_num) {
> +		int tch = *ch - 1;

why tch? can you use more informative names

> +
> +		ret = cpdma_chan_destroy(chan[tch]);
> +		if (ret)
> +			return ret;
> +
> +		dev_info(priv->dev, "destroyed %d %s channel\n", tch,
> +			 (rx ? "rx" : "tx"));
> +		(*ch)--;
> +	}
> +
> +	return 0;
> +}
> +
> +static int cpsw_update_channels(struct net_device *dev,
> +				struct ethtool_channels *ch)
> +{
> +	struct cpsw_priv *priv;
> +	int ret;
> +
> +	priv = netdev_priv(dev);
> +
> +	ret = cpsw_update_channels_res(priv, ch->rx_count, 1);
> +	if (ret)
> +		return ret;
> +
> +	ret = cpsw_update_channels_res(priv, ch->tx_count, 0);
> +	if (ret)
> +		return ret;
> +
> +	if (priv->data.dual_emac) {
> +		int i;
> +		/* mirror channels for another SL */
> +		for (i = 0; i < priv->data.slaves; i++) {
> +			if (priv->slaves[i].ndev == dev)
> +				continue;
> +
> +			cpsw_sync_dual_ch_list(dev, priv->slaves[i].ndev);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int cpsw_set_channels(struct net_device *ndev,
> +			     struct ethtool_channels *chs)
> +{
> +	struct cpsw_priv *priv = netdev_priv(ndev);
> +	int ret;
> +
> +	ret = cpsw_check_ch_settings(priv, chs);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (netif_running(ndev)) {
> +		netif_tx_stop_all_queues(ndev);
> +		cpsw_intr_disable(priv);
> +		netif_dormant_on(ndev);
> +		cpdma_ctlr_stop(priv->dma);
> +	}
> +
> +	ret = cpsw_update_channels(ndev, chs);
> +	if (ret)
> +		goto err;
> +
> +	if (netif_running(ndev)) {
> +		/* inform stach about new count of queues */
> +		ret = netif_set_real_num_tx_queues(ndev, priv->tx_ch_num);
> +		if (ret) {
> +			dev_err(priv->dev, "cannot set real number of tx queues\n");
> +			goto err;
> +		}
> +
> +		ret = netif_set_real_num_rx_queues(ndev, priv->rx_ch_num);
> +		if (ret) {
> +			dev_err(priv->dev, "cannot set real number of rx queues\n");
> +			goto err;
> +		}

You're synchronizing slaves channels for dual_mac mode above, but updating netif real_num_XY_queues()
only for current netdev. Is it correct?

> +
> +		netif_dormant_off(ndev);
> +
> +		if (cpsw_fill_rx_channels(ndev))
> +			goto err;
> +
> +		cpdma_ctlr_start(priv->dma);
> +		cpsw_intr_enable(priv);
> +		netif_tx_start_all_queues(ndev);
> +	}
> +
> +	return 0;
> +err:
> +	dev_err(priv->dev, "cannot update channels number, closing device\n");
> +	dev_close(ndev);
> +	return ret;
> +}
> +
>   static const struct ethtool_ops cpsw_ethtool_ops = {
>   	.get_drvinfo	= cpsw_get_drvinfo,
>   	.get_msglevel	= cpsw_get_msglevel,
> @@ -2098,6 +2284,8 @@ static const struct ethtool_ops cpsw_ethtool_ops = {
>   	.get_regs	= cpsw_get_regs,
>   	.begin		= cpsw_ethtool_op_begin,
>   	.complete	= cpsw_ethtool_op_complete,
> +	.get_channels	= cpsw_get_channels,
> +	.set_channels	= cpsw_set_channels,
>   };
>   
>   static void cpsw_slave_init(struct cpsw_slave *slave, struct cpsw_priv *priv,
> 

-- 
regards,
-grygorii