> > On Tue, Aug 08, 2023 at 10:13:09AM +0200, Bartosz Golaszewski wrote: > > > Ok so upon some further investigation, the actual culprit is in stmmac > > > platform code - it always tries to register an MDIO bus - independent > > > of whether there is an actual mdio child node - unless the MAC is > > > marked explicitly as having a fixed-link. > > > > > > When I fixed that, MAC1's probe is correctly deferred until MAC0 has > > > created the MDIO bus. > > > > > > Even so, isn't it useful to actually reference the shared MDIO bus in some way? > > > > > > If the schematics look something like this: > > > > > > -------- ------- > > > | MAC0 |--MDIO-----| PHY | > > > -------- | | ------- > > > | | > > > -------- | | ------- > > > | MAC1 |-- ----| PHY | > > > -------- ------- > > > > > > Then it would make sense to model it on the device tree? > > > > So I think what you're saying is that MAC0 and MAC1's have MDIO bus > > masters, and the hardware designer decided to tie both together to > > a single set of clock and data lines, which then go to two PHYs. > > The schematics I have are not very clear on that, but now that you > mention this, it's most likely the case. I hope not. That would be very broken. As Russell pointed out, MDIO is not multi-master. You need to check with the hardware designer if the schematics are not clear. > Good point, but it's worse than that: when MAC0 is unbound, it will > unregister the MDIO bus and destroy all PHY devices. These are not > refcounted so they will literally go from under MAC1. Not sure how > this can be dealt with? unbinding is not a normal operation. So i would just live with it, and if root decides to shoot herself in the foot, that is her choice. Andrew
