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From:   Michael Walle <michael@walle.cc>
To:     Andrew Lunn <andrew@lunn.ch>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>
Cc:     "David S . Miller" <davem@davemloft.net>,
        Xu Liang <lxu@maxlinear.com>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Michael Walle <michael@walle.cc>
Subject: [PATCH RFC net-next v2 0/8] net: phy: C45-over-C22 access
Date:   Fri, 25 Mar 2022 22:35:10 +0100
Message-Id: <20220325213518.2668832-1-michael@walle.cc>
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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.

Changes since RFC v1:
 - use __phy_mmd_indirect() in mdiobus_probe_mmd_read()
 - add new properties has_c45 c45_over_c22 (and remove is_c45)
 - drop MDIOBUS_NO_CAP handling, Andrew is preparing a series to
   add probe_capabilities to mark all C45 capable MDIO bus drivers

Michael Walle (8):
  net: phy: mscc-miim: reject clause 45 register accesses
  net: phy: mscc-miim: add probe_capabilities
  net: phy: add error checks in __phy_mmd_indirect() and export it
  net: phy: add error handling for __phy_{read,write}_mmd
  net: phy: support indirect c45 access in get_phy_c45_ids()
  net: phy: add support for C45-over-C22 transfers
  phy: net: introduce phy_promote_to_c45()
  net: phy: mxl-gpy: remove unneeded ops

 .../net/ethernet/hisilicon/hns/hns_ethtool.c  |  4 +-
 drivers/net/mdio/mdio-mscc-miim.c             |  7 ++
 drivers/net/phy/bcm84881.c                    |  2 +-
 drivers/net/phy/marvell10g.c                  |  2 +-
 drivers/net/phy/mxl-gpy.c                     | 31 +------
 drivers/net/phy/phy-core.c                    | 47 +++++++---
 drivers/net/phy/phy.c                         |  6 +-
 drivers/net/phy/phy_device.c                  | 87 ++++++++++++++++---
 drivers/net/phy/phylink.c                     |  8 +-
 include/linux/phy.h                           | 12 ++-
 10 files changed, 136 insertions(+), 70 deletions(-)

-- 
2.30.2