From: Michael Walle <michael@walle.cc>
To: Vladimir Oltean <vladimir.oltean@nxp.com>
Cc: Xiaoliang Yang <xiaoliang.yang_1@nxp.com>,
Vladimir Oltean <olteanv@gmail.com>,
UNGLinuxDriver@microchip.com, alexandre.belloni@bootlin.com,
allan.nielsen@microchip.com,
Claudiu Manoil <claudiu.manoil@nxp.com>,
davem@davemloft.net, idosch@mellanox.com,
joergen.andreasen@microchip.com, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org, Po Liu <po.liu@nxp.com>,
vinicius.gomes@intel.com
Subject: Re: [net-next] net: dsa: felix: disable always guard band bit for TAS config
Date: Mon, 07 Jun 2021 13:26:22 +0200 [thread overview]
Message-ID: <07b1bc11eee83d724d4ddc4ee8378a12@walle.cc> (raw)
In-Reply-To: <20210507121909.ojzlsiexficjjjun@skbuf>
Hi Vladimir, Hi Xiaoliang,
Am 2021-05-07 14:19, schrieb Vladimir Oltean:
> Devices like Felix need the per-queue max SDU from the
> user - if that isn's specified in the netlink message they'll have to
> default to the interface's MTU.
Btw. just to let you and Xiaoliang know:
It appears that PORT_MAX_SDU isn't working as expected. It is used
as a fallback if QMAXSDU_CFG_n isn't set for the guard band
calculation. But it appears to be _not_ used for discarding any
frames. E.g. if you set PORT_MAX_SDU to 500 the port will still
happily send frames larger than 500 bytes. (Unless of course
you hit the guard band of 500 bytes). OTOH QMAXSDU_CFG_n works
as expected, it will discard oversized frames - and presumly will
set the guard band accordingly, I haven't tested this explicitly.
Thus, I wonder what sense PORT_MAX_SDU makes at all. If you set
the guard band to a smaller value than the MTU, you'll also need
to make sure, there will be no larger frames scheduled on that port.
In any case, the workaround is to set QMAXSDU_CFG_n (for all
n=0..7) to the desired max_sdu value instead of using PORT_MAX_SDU.
It might also make sense to check with the IP supplier.
In the case anyone wants to implement that for (upstream) linux ;)
-michael
next prev parent reply other threads:[~2021-06-07 11:26 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-19 10:25 [net-next] net: dsa: felix: disable always guard band bit for TAS config Xiaoliang Yang
2021-04-19 12:38 ` Vladimir Oltean
2021-04-20 3:06 ` [EXT] " Xiaoliang Yang
2021-04-20 8:26 ` Vladimir Oltean
2021-04-20 10:28 ` Xiaoliang Yang
2021-04-20 10:30 ` Vladimir Oltean
2021-04-20 10:42 ` Vladimir Oltean
2021-04-21 2:51 ` Xiaoliang Yang
2021-04-20 10:33 ` Vladimir Oltean
2021-04-20 23:20 ` patchwork-bot+netdevbpf
2021-05-04 17:05 ` Michael Walle
2021-05-04 18:18 ` Vladimir Oltean
2021-05-04 18:38 ` Michael Walle
2021-05-04 18:50 ` Vladimir Oltean
2021-05-04 19:08 ` Michael Walle
2021-05-04 19:17 ` Vladimir Oltean
2021-05-04 20:23 ` Michael Walle
2021-05-04 21:33 ` Vladimir Oltean
2021-05-06 13:25 ` Michael Walle
2021-05-06 13:50 ` Vladimir Oltean
2021-05-06 14:20 ` Michael Walle
2021-05-06 14:41 ` Michael Walle
2021-05-06 15:07 ` Vladimir Oltean
2021-05-06 18:28 ` Michael Walle
2021-05-07 7:16 ` [EXT] " Xiaoliang Yang
2021-05-07 7:35 ` Michael Walle
2021-05-07 11:09 ` Xiaoliang Yang
2021-05-07 12:19 ` Vladimir Oltean
2021-05-07 12:43 ` Michael Walle
2021-06-07 11:26 ` Michael Walle [this message]
2021-06-09 8:06 ` [EXT] " Xiaoliang Yang
2021-06-09 8:41 ` Michael Walle
2021-05-07 12:19 ` Michael Walle
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