There is a race condition in rtl8214fc_power_set(). It reads the
extended page register (reg 30) with __phy_read() without the MDIO bus
lock. Port 0 of the RTL8214FC is the base PHY. The other ports
poll __rtl8214fc_media_is_fibre(), which sets the base PHY's reg 30 to 8
(INTERNAL) for a short time. If port 0 reads in that window, it
"restores" page 8 and stays there. Its standard registers then point to
the internal page, so no link is seen. Every later power cycle reads 8
and writes 8 again.
This fix holds the MDIO bus lock for the whole page-select sequence in
rtl8214fc_power_set().
Signed-off-by: Harm Kroon <hhhkroon@hotmail.com>
Link: https://github.com/openwrt/openwrt/pull/25766
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Harm Kroon
9ae0837c58