From: Vladimir Oltean <olteanv@gmail.com>
To: Felix Fietkau <nbd@nbd.name>
Cc: Sean Wang <sean.wang@mediatek.com>,
Landen Chao <Landen.Chao@mediatek.com>,
DENG Qingfang <dqfext@gmail.com>, Andrew Lunn <andrew@lunn.ch>,
Vivien Didelot <vivien.didelot@gmail.com>,
Florian Fainelli <f.fainelli@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Matthias Brugger <matthias.bgg@gmail.com>,
netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] net: dsa: tag_mtk: add padding for tx packets
Date: Tue, 10 May 2022 19:52:33 +0300 [thread overview]
Message-ID: <20220510165233.yahsznxxb5yq6rai@skbuf> (raw)
In-Reply-To: <5959946d-1d34-49b9-1abe-9f9299cc194e@nbd.name>
On Tue, May 10, 2022 at 04:52:16PM +0200, Felix Fietkau wrote:
>
> On 10.05.22 14:37, Vladimir Oltean wrote:
> > On Tue, May 10, 2022 at 11:40:13AM +0200, Felix Fietkau wrote:
> > > Padding for transmitted packets needs to account for the special tag.
> > > With not enough padding, garbage bytes are inserted by the switch at the
> > > end of small packets.
> >
> > I don't think padding bytes are guaranteed to be zeroes. Aren't they
> > discarded? What is the issue?
> With the broken padding, ARP requests are silently discarded on the receiver
> side in my test. Adding the padding explicitly fixes the issue.
>
> - Felix
Ok, I'm not going to complain too much about the patch, but I'm still
curious where are the so-called "broken" packets discarded.
I think the receiving MAC should be passing up to software a buffer
without the extra padding beyond the L2 payload length (at least that's
the behavior I'm familiar with).
next prev parent reply other threads:[~2022-05-10 16:52 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-10 9:40 [PATCH v2] net: dsa: tag_mtk: add padding for tx packets Felix Fietkau
2022-05-10 12:37 ` Vladimir Oltean
2022-05-10 14:52 ` Felix Fietkau
2022-05-10 16:52 ` Vladimir Oltean [this message]
2022-05-10 22:06 ` Felix Fietkau
2022-05-10 22:21 ` Vladimir Oltean
2022-05-11 8:50 ` Felix Fietkau
2022-05-11 9:32 ` Vladimir Oltean
2022-05-11 12:24 ` Felix Fietkau
2022-05-11 13:22 ` Vladimir Oltean
2022-05-11 14:32 ` Andrew Lunn
2022-05-12 8:51 ` Felix Fietkau
2022-05-12 12:39 ` Andrew Lunn
2022-05-12 13:08 ` Felix Fietkau
2022-05-12 15:32 ` Andrew Lunn
2022-05-11 14:39 ` Andrew Lunn
2022-05-10 21:26 ` Jakub Kicinski
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