The RTL931x indirect access engine has a separate nine-bit extended page
field. The driver leaves it at zero, and otto_emdio_run_cmd() therefore
programs extended page zero for every Clause 22 transaction. This
overrides page selection made through PHY register 30, causing accesses
to private PHY pages to hit extended page zero instead.
Set the field to its 0x1ff "do not change" value for RTL931x Clause 22
reads and writes. This preserves extended page selection made through
PHY register 30 and restores access to its private register pages.
Fixes: 5ebdcac59a ("net: mdio: realtek-rtl9300: Add support for RTL931x")
Signed-off-by: Jonas Jelonek <jonas@jonasjelonek.de>
Acked-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://patch.msgid.link/20260918211955.3955777-1-jonas@jonasjelonek.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
89a8a1eef2