net: dsa: mxl862xx: wait for internal GPHYs before registering MDIO bus - #211
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After the soft reset the switch reports ready once its management
firmware answers commands, but each internal GPHY keeps booting its
own firmware for a window beyond that, and the relay answers even
ID-register reads with an error until it is done.
of_mdiobus_register() scans the DT children once, and a PHY whose ID
read fails is dropped permanently ("MDIO device at address 0 is
missing"); address 0 is scanned first and intermittently loses the
race, leaving lan1 absent until rebind or reboot.
Poll every DT-declared PHY for a valid PHYSID1 before registering the
bus; warn and continue on timeout. Observed and validated on a
BPI-R4 Pro 8x (switch firmware 1.0.70), where management-ready lands
at ~2.4s and the losing window is tens of ms wide.
Signed-off-by: Allie <allie.leth@gmail.com>dangowrt
commented
Aug 10, 2026
Contributor
Please submit this patch also to the upstream Linux netdev mailing list. |
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Fixes the intermittent lan1-missing-at-boot race from t/27755: the one-shot mdiobus scan can hit address 0 while that GPHY is still booting its own firmware, and the single failed ID read drops the port until rebind or reboot.
The fix polls every DT-declared PHY for a valid PHYSID1 before
of_mdiobus_register(), using a quiet relay read (same idiom asmxl862xx_wait_ready()) so the wait produces no error spam. On timeout it warns and continues, so a genuinely absent PHY behaves as today, minus the silence.Validated on two BPI-R4 Pro 8x.
The race is distinct from the CMD-1802 flood fixed by #207 - it reproduced on a tree with those fixes applied. Timing numbers are from this board/firmware; the generous timeout is deliberate since the window is firmware-dependent.