Messages in this thread | ![/](/images/icornerl.gif) | | From | Pierluigi Passaro <> | Subject | Re: [PATCH v2] net: fec: manage corner deferred probe condition | Date | Mon, 16 Jan 2023 19:19:28 +0000 |
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On Mon, Jan 16, 2023 at 8:35 AM Alexander Stein <alexander.stein@ew.tq-group.com> wrote: > Hi, > > Am Sonntag, 15. Januar 2023, 23:23:51 CET schrieb Pierluigi Passaro: > > On Sun, Jan 15, 2023 at 10:56 PM Andrew Lunn <andrew@lunn.ch> wrote: > > > On Sun, Jan 15, 2023 at 10:38:04PM +0100, Pierluigi Passaro wrote: > > > > For dual fec interfaces, external phys can only be configured by fec0. > > > > When the function of_mdiobus_register return -EPROBE_DEFER, the driver > > > > is lately called to manage fec1, which wrongly register its mii_bus as > > > > fec0_mii_bus. > > > > When fec0 retry the probe, the previous assignement prevent the MDIO bus > > > > registration. > > > > Use a static boolean to trace the orginal MDIO bus deferred probe and > > > > prevent further registrations until the fec0 registration completed > > > > succesfully. > > > > > > The real problem here seems to be that fep->dev_id is not > > > deterministic. I think a better fix would be to make the mdio bus name > > > deterministic. Use pdev->id instead of fep->dev_id + 1. That is what > > > most mdiobus drivers use. > > > > Actually, the sequence is deterministic, fec0 and then fec1, > > but sometimes the GPIO of fec0 is not yet available. > > Not in every case though. On i.MX6UL has the following memory map for FEC: > * FEC2: 0x020b4000 > * FEC1: 0x02188000 > > Which essentially means that fec2 will be probed first. > This is actually the expected behaviour, by FEC0 I refer to the 1st instance of FEC, no matter the alias used for it: apologizing for the misleading notation. For iMX6UL, when both the FEC are present, the MDIO is owned by fec@0x020b4000, which is the 1st instance of FEC. > > > The EPROBE_DEFER does not prevent the second instance from being probed. > > This is the origin of the problem. > > Is this the actual cause? There is also a problem in the case above if the > MDIO controlling interface (fec2) is not probed first, e.g. using fec1 for > MDIO access. But then again there is i.MX6ULG1 which only has fec1 > interface... > I'm not familiar with iMX6ULG1, but I would expect that its device tree disables one of the 2 fec: this patch is relevant only for dual FEC configuration. > > Best regards, > Alexander
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