On 3/24/21 10:09 PM, 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.
Hi,
The PMAC in the xrx200 has 4 TX queues and 8 RX queues. We can not map
one queue to each port as there are more ports than queues. I am also
unsure if the DSL part which is using an out of tree driver uses some of
these DMA resources.
Is it possible to configure a mapping between a DSA bridge and a queue
on the mater device with tc from user space? We could expose these 4 TX
queues on the mac driver to Linux and then Linux configure somehow a
mapping between ports or bridges and queues.
Hauke
