[PATCH RFC net-next 0/5] net: phy: C45-over-C22 access

Michael Walle
2022-03-23T18:34:52Z

Hi,

This is the result of this discussion:
https://lore.kernel.org/netdev/240354b0a54b37e8b5764773711b8aa3@walle.cc/

The goal here is to get the GYP215 and LAN8814 running on the Microchip
LAN9668 SoC. The LAN9668 suppports one external bus and unfortunately, the
LAN8814 has a bug which makes it impossible to use C45 on that bus.
Fortunately, it was the intention of the GPY215 driver to be used on a C22
bus. But I think this could have never really worked, because the
phy_get_c45_ids() will always do c45 accesses and thus on MDIO bus drivers
which will correctly check for the MII_ADDR_C45 flag and return -EOPNOTSUPP
the function call will fail and thus gpy_probe() will fail. This series
tries to fix that and will lay the foundation to add a workaround for the
LAN8814 bug by forcing an MDIO bus to be c22-only.

At the moment, the probe_capabilities is taken into account to decide if
we have to use C45-over-C22. What is still missing from this series is the
handling of a device tree property to restrict the probe_capabilities to
c22-only.

Since net-next is closed, this is marked as RFC to get some early feedback.

Michael Walle (5):
net: phy: mscc-miim: reject clause 45 register accesses
net: phy: support indirect c45 access in get_phy_c45_ids()
net: phy: mscc-miim: add probe_capabilities
net: phy: introduce is_c45_over_c22 flag
net: phylink: handle the new is_c45_over_c22 property

drivers/net/mdio/mdio-mscc-miim.c | 7 ++++
drivers/net/phy/mxl-gpy.c | 2 +-
drivers/net/phy/phy_device.c | 65 ++++++++++++++++++++++++++-----
drivers/net/phy/phylink.c | 2 +-
include/linux/phy.h | 4 +-
5 files changed, 68 insertions(+), 12 deletions(-)

--
2.30.2