From: Vladimir Oltean <olteanv@gmail.com>
To: Florian Fainelli <f.fainelli@gmail.com>
Cc: Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
netdev@vger.kernel.org, Hauke Mehrtens <hauke@hauke-m.de>,
andrew@lunn.ch, vivien.didelot@gmail.com, davem@davemloft.net,
kuba@kernel.org
Subject: Re: lantiq_xrx200: Ethernet MAC with multiple TX queues
Date: Thu, 25 Mar 2021 00:21:14 +0200 [thread overview]
Message-ID: <20210324222114.4uh5modod373njuh@skbuf> (raw)
In-Reply-To: <874dd389-dd67-65a6-8ccc-cc1d9fa904a2@gmail.com>
Hi Florian,
On Wed, Mar 24, 2021 at 02:09:02PM -0700, Florian Fainelli wrote:
>
>
> On 3/24/2021 1:13 PM, Vladimir Oltean wrote:
> > Hi Martin,
> >
> > On Wed, Mar 24, 2021 at 09:04:16PM +0100, Martin Blumenstingl wrote:
> >> Hello,
> >>
> >> the PMAC (Ethernet MAC) IP built into the Lantiq xRX200 SoCs has
> >> support for multiple (TX) queues.
> >> This MAC is connected to the SoC's built-in switch IP (called GSWIP).
> >>
> >> Right now the lantiq_xrx200 driver only uses one TX and one RX queue.
> >> The vendor driver (which mixes DSA/switch and MAC functionality in one
> >> driver) uses the following approach:
> >> - eth0 ("lan") uses the first TX queue
> >> - eth1 ("wan") uses the second TX queue
> >>
> >> With the current (mainline) lantiq_xrx200 driver some users are able
> >> to fill up the first (and only) queue.
> >> This is why I am thinking about adding support for the second queue to
> >> the lantiq_xrx200 driver.
> >>
> >> My main question is: how do I do it properly?
> >> Initializing the second TX queue seems simple (calling
> >> netif_tx_napi_add for a second time).
> >> But how do I choose the "right" TX queue in xrx200_start_xmit then?
>
> If you use DSA you will have a DSA slave network device which will be
> calling into dev_queue_xmit() into the DSA master which will be the
> xrx200 driver, so it's fairly simple for you to implement a queue
> selection within the xrx200 tagger for instance.
>
> You can take a look at how net/dsa/tag_brcm.c and
> drivers/net/ethernet/broadcom/bcmsysport.c work as far as mapping queues
> from the DSA slave network device queue/port number into a queue number
> for the DSA master.
What are the benefits of mapping packets to TX queues of the DSA master
from the DSA layer?
next prev parent reply other threads:[~2021-03-24 22:22 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-24 20:04 lantiq_xrx200: Ethernet MAC with multiple TX queues Martin Blumenstingl
2021-03-24 20:13 ` Vladimir Oltean
2021-03-24 21:09 ` Florian Fainelli
2021-03-24 22:21 ` Vladimir Oltean [this message]
2021-03-24 23:07 ` Florian Fainelli
2021-03-25 1:18 ` Vladimir Oltean
2021-03-25 3:08 ` Florian Fainelli
2021-03-25 19:29 ` Martin Blumenstingl
2021-03-24 22:50 ` Hauke Mehrtens
2021-03-24 22:58 ` Florian Fainelli
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