[RFC PATCH net-next v2 0/5] net: dsa: qca8k: add a QCA8337 CPU PHY consumer

[Yongzhao Chen <yongzhao.derek@gmail.com>]

Following Andrew's feedback on the v1 RFC, shared-port PHY flag plumbing
now includes its consumer within the same series. To clarify a prior
misunderstanding, the qca83xx PHY driver already exists upstream; patch
5 supplies the new flag consumer alongside internal CPU-PHY selection in
qca8k.

The minimal topology has one CPU link: a conduit PHY connects through
MDI to QCA8337 PHY4, belonging to switch port 5. The two sides have
distinct phy-handles. A user port provides the data path; ports 0 and 6
are unused. The existing binding accepts an ethernet phandle, phy-mode
and phy-handle on port 5. A reduced fixture based on the documented
Redmi AX5400 wiring passes dtc and the complete net-next schema set. It
is a binding fixture, not a bootable board port.

The pinned net-next base lacks an IPQ5018 Ethernet MAC driver and an
RA74 DTS description. Consequently, this series cannot demonstrate a
runnable RA74 platform upstream, though this does not preclude other
hardware implementations. We would appreciate review of whether this
code-level qca83xx consumer is sufficient scope for the RFC while the
board and MAC support remain downstream.

In this revision:
- Patch 3 serializes MTU updates with phylink link-up/down and port
  enable/disable. It restores each CPU port's original TXMAC/RXMAC
  state, so a link-down port stays down while LINK_AUTO is preserved.
  Failed status reads or MAC pauses abort before the frame-size write;
  restoration failures are logged even if the original operation failed.
- Patch 4 defines the shared switch-to-PHY flag and marks QCA8337
  internal CPU PHYs for SmartSpeed suppression.
- Patch 5 consumes the flag in qca8337_soft_reset() and before the resume
  BMCR reset. It clears enable and bypass-timer bits, preserves other
  register bits and returns an MDIO error without issuing the reset.

Validation:
- All five exported patches pass checkpatch --strict and git mailinfo;
  each parsed commit message retains its DCO sign-off. Independent
  sequential application reproduces the tree.
- ASan and UBSan function-model suites pass 7,189 CPU-selection, MDIO
  and MTU cases plus four resume cases, with 14 negative controls.
- The current qca8k-common.o, qca8k-8xxx.o and qca83xx.o pass x86_64
  and ARM64 allyesconfig/allmodconfig W=1 builds without KCFLAGS overrides.
- Physical hardware testing on upstream net-next has not been performed
  due to the absence of upstream IPQ5018 MAC driver and board DTS.

Changes from v1:
- Clarified that qca83xx is already present upstream; patch 5 provides
  the SmartSpeed flag consumer.
- Added internal CPU-PHY support (retaining Ziyang Huang's authorship).
- Serialized MTU reconfiguration with MAC link-state changes and restored
  each port's original TXMAC/RXMAC bits while preserving LINK_AUTO.
- Narrowed MDIO address filtering to preserve external user-port
  behavior.

Original RFC:
https://lore.kernel.org/netdev/20260919085406.1395-1-yongzhao.derek@gmail.com/

Maintainer response:
https://lore.kernel.org/netdev/59975387-5539-47e7-bcca-4a5ed0a84bad@lunn.ch/

Yongzhao Chen (4):
  net: dsa: pass PHY flags when connecting shared ports
  net: dsa: qca8k: serialize CPU MAC pause during MTU changes
  net: dsa: qca8k: flag QCA8337 internal CPU PHYs for SmartSpeed
  net: phy: qca83xx: disable SmartSpeed before resetting CPU PHYs

Ziyang Huang (1):
  net: dsa: qca8k: support an internal PHY as the CPU port

 Documentation/networking/dsa/dsa.rst |  2 +
 MAINTAINERS                          |  1 +
 drivers/net/dsa/bcm_sf2.c            |  4 ++
 drivers/net/dsa/microchip/ksz8.c     |  4 ++
 drivers/net/dsa/qca/qca8k-8xxx.c     | 37 ++++++++++-------
 drivers/net/dsa/qca/qca8k-common.c   | 79 +++++++++++++++++++++++++++++-------
 drivers/net/dsa/qca/qca8k.h          |  2 +
 drivers/net/phy/qcom/qca83xx.c       | 32 +++++++++++++--
 include/linux/qca83xx.h              | 11 ++++++
 net/dsa/port.c                       |  6 ++-
 10 files changed, 144 insertions(+), 34 deletions(-)
 create mode 100644 include/linux/qca83xx.h

base-commit: 8830e65ed46de41f849eefb8ba227d4852c460f6
-- 
2.43.0