[PATCH net-next v7 00/15] net: phy: Introduce PHY ports representation
Maxime Chevallier
maxime.chevallier at bootlin.com
Mon Jun 30 07:32:59 PDT 2025
Hi everyone,
Here's a V7 for the ongoing support for Ethernet media-side port
support.
This V7 addresses some of the shortcomings, including :
- A rework of the way we assign each port's supported field
- The support for combo-ports on the marvell 88x3310
- Patch 2 is back, it was removed after Russell's comments in RFCV2.
At that time, Russell said :
" > Mark BaseT as being a 4-lanes mode.
This is a problem:
1.4.50 10BASE-T: IEEE 802.3 Physical Layer specification for a 10 Mb/s
CSMA/CD local area network over two pairs of twisted-pair telephone
wire. (See IEEE Std 802.3, Clause 14.)
Then we have the 100BASE-T* family, which can be T1, T2, T4 or TX.
T1 is over a single balanced twisted pair. T2 is over two pairs of
Cat 3 or better. T4 is over four pairs of Cat3/4/5.
The common 100BASE-T* type is TX, which is over two pairs of Cat5.
This is sadly what the ethtool 100baseT link modes are used to refer
to.
We do have a separate link mode for 100baseT1, but not 100baseT4.
So, these ethtool modes that are of the form baseT so far are
describing generally two pairs, one pair in each direction. (T1 is
a single pair that is bidirectional.)
It's only once we get to 1000BASE-T (1000baseT) that we get to an
ethtool link mode that has four lanes in a bidirectional fashion.
So, simply redefining this ends up changing 10baseT and 100baseT from
a single lane in each direction to four lanes (and is a "lane" here
defined as the total number of pairs used for communication in both
directions, or the total number of lanes used in either direction.
Hence, I'm not sure this makes sense."
Russell it completely right, and I failed to make my point at that time.
Now, I think this patch does make sense as :
- We treat BaseT1 as its own medium
- In patch 3, we enforce the following :
- 10 and 100BaseT work on 2 pairs, but can also work on a 4-pair port
- 1000BaseT and above need 4 pairs
I'm again open for any kind of discussion :)
Before going into the details, a few important notes :
- This is only a first phase. It instantiates the port, and leverage
that to make the MAC <-> PHY <-> SFP usecase simpler.
- Next phase will deal with controlling the port state, as well as the
netlink uAPI for that.
- The end-goal is to enable support for complex port MUX. This
preliminary work focuses on PHY-driven ports, but this will be
extended to support muxing at the MII level (Multi-phy, or compo PHY
+ SFP as found on Turris Omnia for example).
- The naming is definitely not set in stone. I named that "phy_port",
but this may convey the false sense that this is phylib-specific.
Even the word "port" is not that great, as it already has several
different meanings in the net world (switch port, devlink port,
etc.). I used the term "connector" in the binding.
A bit of history on that work :
The end goal that I personnaly want to achieve is :
+ PHY - RJ45
|
MAC - MUX -+ PHY - RJ45
After many discussions here on netdev@, but also at netdevconf[1] and
LPC[2], there appears to be several analoguous designs that exist out
there.
[1] : https://netdevconf.info/0x17/sessions/talk/improving-multi-phy-and-multi-port-interfaces.html
[2] : https://lpc.events/event/18/contributions/1964/ (video isn't the
right one)
Take the MAchiatobin, it has 2 interfaces that looks like this :
MAC - PHY -+ RJ45
|
+ SFP - Whatever the module does
Now, looking at the Turris Omnia, we have :
MAC - MUX -+ PHY - RJ45
|
+ SFP - Whatever the module does
We can find more example of this kind of designs, the common part is
that we expose multiple front-facing media ports. This is what this
current work aims at supporting. As of right now, it does'nt add any
support for muxing, but this will come later on.
This first phase focuses on phy-driven ports only, but there are already
quite some challenges already. For one, we can't really autodetect how
many ports are sitting behind a PHY. That's why this series introduces a
new binding. Describing ports in DT should however be a last-resort
thing when we need to clear some ambiguity about the PHY media-side.
The only use-cases that we have today for multi-port PHYs are combo PHYs
that drive both a Copper port and an SFP (the Macchiatobin case). This
in itself is challenging and this series only addresses part of this
support, by registering a phy_port for the PHY <-> SFP connection. The
SFP module should in the end be considered as a port as well, but that's
not yet the case.
However, because now PHYs can register phy_ports for every media-side
interface they have, they can register the capabilities of their ports,
which allows making the PHY-driver SFP case much more generic.
Let me know what you think, I'm all in for discussions :)
Regards,
Changes in V7:
- Move ethtool_medium_get_supported to phy_caps
- support combo-ports, each with a given set of supported modes
- Introduce the notion of 'not-described' ports
Changes in V6:
- Fixed kdoc on patch 3
- Addressed a missing port-ops registration for the Marvell 88x2222
driver
- Addressed a warning reported by Simon on the DP83822 when building
without CONFIG_OF_MDIO
Changes in V5 :
- renamed the bindings to use the term "connector" instead of "port"
- Rebased, and fixed some issues reported on the 83822 driver
- Use phy_caps
Changes in V4 :
- Introduced a kernel doc
- Reworked the mediums definitions in patch 2
- QCA807x now uses the generic SFP support
- Fixed some implementation bugs to build the support list based on the
interfaces supported on a port
V6: https://lore.kernel.org/netdev/20250507135331.76021-1-maxime.chevallier@bootlin.com/
V5: https://lore.kernel.org/netdev/20250425141511.182537-1-maxime.chevallier@bootlin.com/
V4: https://lore.kernel.org/netdev/20250213101606.1154014-1-maxime.chevallier@bootlin.com/
V3: https://lore.kernel.org/netdev/20250207223634.600218-1-maxime.chevallier@bootlin.com/
RFC V2: https://lore.kernel.org/netdev/20250122174252.82730-1-maxime.chevallier@bootlin.com/
RFC V1: https://lore.kernel.org/netdev/20241220201506.2791940-1-maxime.chevallier@bootlin.com/
Maxime
Maxime Chevallier (15):
dt-bindings: net: Introduce the ethernet-connector description
net: ethtool: common: Indicate that BaseT works on up to 4 lanes
net: ethtool: Introduce ETHTOOL_LINK_MEDIUM_* values
net: phy: Introduce PHY ports representation
net: phy: dp83822: Add support for phy_port representation
net: phy: Create a phy_port for PHY-driven SFPs
net: phy: Introduce generic SFP handling for PHY drivers
net: phy: marvell-88x2222: Support SFP through phy_port interface
net: phy: marvell: Support SFP through phy_port interface
net: phy: marvell10g: Support SFP through phy_port
net: phy: at803x: Support SFP through phy_port interface
net: phy: qca807x: Support SFP through phy_port interface
net: phy: Only rely on phy_port for PHY-driven SFP
net: phy: dp83822: Add SFP support through the phy_port interface
Documentation: networking: Document the phy_port infrastructure
.../bindings/net/ethernet-connector.yaml | 47 +++
.../devicetree/bindings/net/ethernet-phy.yaml | 18 +
Documentation/networking/index.rst | 1 +
Documentation/networking/phy-port.rst | 111 ++++++
MAINTAINERS | 3 +
drivers/net/phy/Makefile | 2 +-
drivers/net/phy/dp83822.c | 78 +++--
drivers/net/phy/marvell-88x2222.c | 98 +++---
drivers/net/phy/marvell.c | 100 +++---
drivers/net/phy/marvell10g.c | 47 +--
drivers/net/phy/phy-caps.h | 5 +
drivers/net/phy/phy_caps.c | 58 ++++
drivers/net/phy/phy_device.c | 327 +++++++++++++++++-
drivers/net/phy/phy_port.c | 173 +++++++++
drivers/net/phy/qcom/at803x.c | 64 +---
drivers/net/phy/qcom/qca807x.c | 75 ++--
include/linux/ethtool.h | 44 ++-
include/linux/phy.h | 38 +-
include/linux/phy_port.h | 97 ++++++
include/uapi/linux/ethtool.h | 20 ++
net/ethtool/common.c | 267 ++++++++------
21 files changed, 1284 insertions(+), 389 deletions(-)
create mode 100644 Documentation/devicetree/bindings/net/ethernet-connector.yaml
create mode 100644 Documentation/networking/phy-port.rst
create mode 100644 drivers/net/phy/phy_port.c
create mode 100644 include/linux/phy_port.h
--
2.49.0
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