From: Andrew Lunn <andrew@lunn.ch>
To: Maxime Chevallier <maxime.chevallier@bootlin.com>
Cc: "Nicolai Buchwitz" <nb@tipi-net.de>,
"Andrew Lunn" <andrew+netdev@lunn.ch>,
"Jakub Kicinski" <kuba@kernel.org>,
davem@davemloft.net, "Eric Dumazet" <edumazet@google.com>,
"Paolo Abeni" <pabeni@redhat.com>,
"Simon Horman" <horms@kernel.org>,
"Maxime Coquelin" <mcoquelin.stm32@gmail.com>,
"Alexandre Torgue" <alexandre.torgue@foss.st.com>,
"Russell King" <linux@armlinux.org.uk>,
thomas.petazzoni@bootlin.com,
"Alexis Lothoré" <alexis.lothore@bootlin.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-stm32@st-md-mailman.stormreply.com
Subject: Re: [PATCH net-next 1/2] net: stmmac: dwmac4: Read the UC filter size from hardware capabilities
Date: Tue, 1 Sep 2026 02:26:26 +0200 [thread overview]
Message-ID: <b2fbcec7-90ee-4a6f-bd15-32e4e1ff1a47@lunn.ch> (raw)
In-Reply-To: <480f15e2-e045-46b7-89af-1fbcefd3c4eb@bootlin.com>
> Yeah but dwmac4 has a hash filter, but same as the UC filter it's just not plumbed
> in :/
>
> Let's leave this flag here, hash filter addition for MC filtering is coming-up, so let's not
> drop it now only to re-enable it after, one of the other wonderful discoveries found by
> running the selftests...
I assume you can put a MC address in a perfect match filter? You can
perfectly match a multicast address just as well as a unicast address.
The hash filter is less accurate, but again can be used to match a
unicast or multicast address, and then you need additional filtering
in software, which Linux will do.
So it seems to me, you should use a perfect match filters if you have
one available, independent of unicast or multicast, and only use a
hash filter if you have run out of perfect match filters.
A IPv6 interface will be listening on a multicast address for
Neighbour discovery. It would be good to do a perfect match on it...
Andrew
next prev parent reply other threads:[~2026-09-01 0:26 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-31 7:01 [PATCH net-next 0/2] net: stmmac: dwmac4: Auto-discover UC filter size Maxime Chevallier
2026-08-31 7:01 ` [PATCH net-next 1/2] net: stmmac: dwmac4: Read the UC filter size from hardware capabilities Maxime Chevallier
2026-08-31 12:04 ` Nicolai Buchwitz
2026-08-31 12:15 ` Maxime Chevallier
2026-08-31 12:26 ` Nicolai Buchwitz
2026-09-01 0:26 ` Andrew Lunn [this message]
2026-09-01 7:04 ` Maxime Chevallier
2026-09-01 12:38 ` Andrew Lunn
2026-09-01 7:08 ` Maxime Chevallier
2026-08-31 7:01 ` [PATCH net-next 2/2] net: stmmac: dwmac4: Use the full perfect filter ability for UC filter Maxime Chevallier
2026-08-31 12:06 ` Nicolai Buchwitz
2026-09-01 0:12 ` Andrew Lunn
2026-09-01 6:37 ` Maxime Chevallier
2026-09-01 12:21 ` Andrew Lunn
2026-09-01 12:27 ` Maxime Chevallier
2026-09-01 12:50 ` Andrew Lunn
2026-09-03 9:00 ` [PATCH net-next 0/2] net: stmmac: dwmac4: Auto-discover UC filter size patchwork-bot+netdevbpf
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