From: "Russell King (Oracle)" <linux@armlinux•org.uk>
To: Andrew Lunn <andrew@lunn•ch>
Cc: "Naveen Mamindlapalli" <naveenm@marvell•com>,
"Björn Töpel" <bjorn@kernel•org>,
netdev@vger•kernel.org, "Donald Hunter" <donald.hunter@gmail•com>,
"Jakub Kicinski" <kuba@kernel•org>,
"David S. Miller" <davem@davemloft•net>,
"Eric Dumazet" <edumazet@google•com>,
"Paolo Abeni" <pabeni@redhat•com>,
"Simon Horman" <horms@kernel•org>,
"Saeed Mahameed" <saeedm@nvidia•com>,
"Tariq Toukan" <tariqt@nvidia•com>,
"Leon Romanovsky" <leon@kernel•org>,
"Andrew Lunn" <andrew+netdev@lunn•ch>,
"Maxime Chevallier" <maxime.chevallier@bootlin•com>,
"Michael Chan" <michael.chan@broadcom•com>,
"Hariprasad Kelam" <hkelam@marvell•com>,
"Ido Schimmel" <idosch@nvidia•com>,
"Danielle Ratson" <danieller@nvidia•com>,
linux-kernel@vger•kernel.org, linux-rdma@vger•kernel.org
Subject: Re: [RFC net-next v2 0/6] ethtool: Generic loopback support
Date: Wed, 11 Mar 2026 16:52:34 +0000 [thread overview]
Message-ID: <abGd0kJb0zEn2Yzb@shell.armlinux.org.uk> (raw)
In-Reply-To: <0aa736b4-2c1c-4317-bcc1-1d4c9ad49380@lunn.ch>
On Wed, Mar 11, 2026 at 01:32:09PM +0100, Andrew Lunn wrote:
> > > > With a SERDES component, the mapping becomes cleaner:
> > > > component name supported
> > > > MAC mac near-end
> > > > SERDES serdes-ned near-end
> > > > SERDES serdes-nea near-end
> > > > SERDES serdes-fed far-end
> > >
> > > If Linux where to drive the SERDES, what part of Linux would it be?
> > > Generic PHY? How does your SERDES hardware block fit into 802.3? Which
> > > clause describes it?
> >
> > Hi Andrew,
> >
> > On OcteonTx2 SoC, the SerDes (GSERM) is a HW block integrated into the
> > SoC die. It is not on an MDIO bus or any bus that Linux can enumerate.
> > The block is fully managed by the firmware running on the SoC. The NIC
> > driver configures it indirectly through firmware mailbox commands.
> >
> > The data path looks like:
> > MAC (RPM) --- SerDes (GSERM) --- module/PHY
> >
> > In 802.3 terms, the closest match would be PMA. The GSERM handles
> > serialization/deserialization and the analog front-end.
>
> A Linux Generic PHY is probably also PMA.
>
> 802.3 says very little about SERDES, it is not a well defined term. So
> i think we want PCS and PMA, not SERDES as a loopback point.
That's a good point. I'm wondeirng whether to change "serdes" /
"SerDes" in my stmmac patches to be "pma".
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
prev parent reply other threads:[~2026-03-11 16:52 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-08 12:40 [RFC net-next v2 0/6] ethtool: Generic loopback support Björn Töpel
2026-03-08 12:40 ` [RFC net-next v2 1/6] ethtool: Add loopback netlink UAPI definitions Björn Töpel
2026-03-09 14:16 ` Maxime Chevallier
2026-03-09 14:59 ` Björn Töpel
2026-03-09 16:45 ` Andrew Lunn
2026-03-10 10:23 ` Maxime Chevallier
2026-03-10 13:56 ` Andrew Lunn
2026-03-08 12:40 ` [RFC net-next v2 2/6] ethtool: Add loopback GET/SET netlink implementation Björn Töpel
2026-03-09 7:34 ` Maxime Chevallier
2026-03-09 8:21 ` Björn Töpel
2026-03-09 14:51 ` Björn Töpel
2026-03-09 16:14 ` Maxime Chevallier
2026-03-08 12:40 ` [RFC net-next v2 3/6] ethtool: add CMIS loopback helpers for module loopback control Björn Töpel
2026-03-08 12:40 ` [RFC net-next v2 4/6] selftests: drv-net: Add loopback driver test Björn Töpel
2026-03-08 12:40 ` [RFC net-next v2 5/6] netdevsim: Add module EEPROM simulation via debugfs Björn Töpel
2026-03-08 12:40 ` [RFC net-next v2 6/6] selftests: drv-net: Add CMIS loopback netdevsim test Björn Töpel
2026-03-09 13:49 ` [RFC net-next v2 0/6] ethtool: Generic loopback support Naveen Mamindlapalli
2026-03-09 14:55 ` Björn Töpel
2026-03-10 7:35 ` Naveen Mamindlapalli
2026-03-10 14:00 ` Andrew Lunn
2026-03-11 5:59 ` Naveen Mamindlapalli
2026-03-11 12:32 ` Andrew Lunn
2026-03-11 16:52 ` Russell King (Oracle) [this message]
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