Re: [PATCH 2/2] net: mdio: reset PHY before attempting to access registers in fwnode_mdiobus_register_phy
From: Maxime Chevallier
Date: Mon Oct 13 2025 - 10:31:33 EST
Hi,
On 13/10/2025 15:55, Buday Csaba wrote:
When the ID of an ethernet PHY is not provided by the 'compatible'
string in the device tree, its actual ID is read via the MDIO bus.
For some PHYs this could be unsafe, since a hard reset may be
necessary to safely access the MDIO registers.
This patch makes it possible to hard-reset an ethernet PHY before
attempting to read the ID, via a new device tree property, called:
`reset-phy-before-probe`.
There were previous attempts to implement such functionality, I
tried to collect a few of these (see links).
Link: https://lore.kernel.org/lkml/1499346330-12166-2-git-send-email-richard.leitner@xxxxxxxxxxx/
Link: https://lore.kernel.org/all/20230405-net-next-topic-net-phy-reset-v1-0-7e5329f08002@xxxxxxxxxxxxxx/
Link: https://lore.kernel.org/netdev/20250709133222.48802-4-buday.csaba@xxxxxxxxx/
Signed-off-by: Buday Csaba <buday.csaba@xxxxxxxxx>
This should probably be accompanied by a DT binding update,
with some justification that this is indeed HW description
and not OS confguration.
At least the use of the term "probe" in the property makes this
sound like OS configuration, maybe something like :
"phy-id-needs-reset" ?
Maxime