> -----Original Message-----
> From: David Miller <da...@davemloft.net>
> Sent: Thursday, June 6, 2019 9:03 PM
> To: Ioana Ciocoi Radulescu <ruxandra.radule...@nxp.com>
> Cc: netdev@vger.kernel.org; Ioana Ciornei <ioana.cior...@nxp.com>
> Subject: Re: [PATCH net-next v2 2/3] dpaa2-eth: Support multiple traffic
> classes on Tx
>
> From: Ioana Radulescu <ruxandra.radule...@nxp.com>
> Date: Thu, 6 Jun 2019 11:50:28 +0300
>
> > DPNI objects can have multiple traffic classes, as reflected by
> > the num_tc attribute. Until now we ignored its value and only
> > used traffic class 0.
> >
> > This patch adds support for multiple Tx traffic classes; the skb
> > priority information received from the stack is used to select the
> > hardware Tx queue on which to enqueue the frame.
> >
> > Signed-off-by: Ioana Radulescu <ruxandra.radule...@nxp.com>
> > ---
> > v2: Extra processing on the fast path happens only when TC is used
> >
> > drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c | 47
> ++++++++++++++++--------
> > drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h | 9 ++++-
> > 2 files changed, 40 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
> b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
> > index a12fc45..98de092 100644
> > --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
> > +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
> > @@ -757,6 +757,7 @@ static netdev_tx_t dpaa2_eth_tx(struct sk_buff
> *skb, struct net_device *net_dev)
> > u16 queue_mapping;
> > unsigned int needed_headroom;
> > u32 fd_len;
> > + u8 prio = 0;
> > int err, i;
> >
> > percpu_stats = this_cpu_ptr(priv->percpu_stats);
> > @@ -814,6 +815,18 @@ static netdev_tx_t dpaa2_eth_tx(struct sk_buff
> *skb, struct net_device *net_dev)
> > * a queue affined to the same core that processed the Rx frame
> > */
> > queue_mapping = skb_get_queue_mapping(skb);
> > +
> > + if (net_dev->num_tc) {
> > + prio = netdev_txq_to_tc(net_dev, queue_mapping);
> > + /* Hardware interprets priority level 0 as being the highest,
> > + * so we need to do a reverse mapping to the netdev tc index
> > + */
> > + prio = net_dev->num_tc - prio - 1;
> > + /* We have only one FQ array entry for all Tx hardware
> queues
> > + * with the same flow id (but different priority levels)
> > + */
> > + queue_mapping %= dpaa2_eth_queue_count(priv);
>
> This doesn't make any sense.
>
> queue_mapping came from skb_get_queue_mapping().
>
> The core limits the queue mapping value to whatever you told the
> generic networking layer was the maximum number of queues.
>
> And you set that to dpaa2_eth_queue_count():
>
> /* Set actual number of queues in the net device */
> num_queues = dpaa2_eth_queue_count(priv);
> err = netif_set_real_num_tx_queues(net_dev, num_queues);
>
> Therfore the modulus cannot be needed.
True, at this point it's not needed yet. This patch adds code in
preparation for patch 3/3, which does modify the maximum
number of queues on the device when multiple TCs are configured
via mqprio.
I can move it to the next patch where it's use is more clear.
Thanks,
Ioana
