Re: [PATCH] net: phy: realtek: add support for RTL8366S Gigabit PHY

[Simon Horman <horms@kernel.org>]

On Thu, Jul 25, 2024 at 01:05:19PM -0400, Mark Mentovai wrote:
> The PHY built in to the Realtek RTL8366S switch controller was
> previously supported by genphy_driver. This PHY does not implement MMD
> operations. Since 9b01c885be36 (2023-02-13, in 6.3), MMD register reads
> have been made during phy_probe to determine EEE support. For
> genphy_driver, these reads are transformed into 802.3 annex 22D clause
> 45-over-clause 22 mmd_phy_indirect operations that perform MII register
> writes to MII_MMD_CTRL and MII_MMD_DATA. This overwrites those two MII
> registers, which on this PHY are reserved and have another function,
> rendering the PHY unusable while so configured.
> 
> Proper support for this PHY is restored by providing a phy_driver that
> declares MMD operations as unsupported by using the helper functions
> provided for that purpose, while remaining otherwise identical to
> genphy_driver.
> 
> Fixes: 9b01c885be36 ("net: phy: c22: migrate to genphy_c45_write_eee_adv()")
> Fixes: https://github.com/openwrt/openwrt/issues/15981

nit: AFAIK, the line immediately above is not a correct use of the Fixes
     tag. I think Link or Closes would be appropriate instead.

> Link: https://github.com/openwrt/openwrt/issues/15739
> Reported-by: Russell Senior <russell@personaltelco.net>
> Signed-off-by: Mark Mentovai <mark@mentovai.com>

Also, as a fix, this should be targeted at the net tree.

	Subject: [PATCH net] ...

Please see https://docs.kernel.org/process/maintainer-netdev.html