Re: Broken ethernet on SolidRun cubox-i

[Michael Walle <michael@walle.cc>]

Am 2020-12-26 13:34, schrieb Russell King - ARM Linux admin:
> On Sat, Dec 26, 2020 at 01:18:01PM +0100, Michael Walle wrote:
>> Thus I suspect your commit 86b08bd5b994 ("ARM: dts: imx6-sr-som: add
>> ethernet PHY configuration") to be the culprit ;) This will pin the
>> PHY to address 0. I don't know how it was done before; like was there
>> autoprobing if there is no "phy-handle" or did the bootloader fix that
>> inplace. I don't have any cubox-i.
> 
> There is the need to move the AT803x quirk handling into DT rather than
> using the PHY quirk system - the problem is, the PHY quirk system
> applies the quirks to every iMX6 platform out there, whether the quirk
> is right or wrong for that board.
> 
> I'd forgotten that there were boards out there with this problem...
> the PHY address configuration is done via the LED_ACT pin, and SolidRun
> omitted a pull resistor on it, so it "floats" with the leakage current
> of the LED/pin - resulting in it sometimes appearing at address 0 and
> sometimes at address 4.

Mh, I've guessed that too, but there must be more to it. The datasheet
says it has an internal weak pull-up. Or Atheros messed up and it 
doesn't
reliably work if there is actually an LED attached to it. But then, why
would any other stronger pull-up/down work..

> I suppose there's no option but to revert the commit - but it needs to
> be properly documented /why/ that is the case, and comments added to
> ar8035_phy_fixup() in arch/arm/mach-imx/mach-imx6q.c to say why that
> quirk can't be removed.

Will you take care of that? Like I said, I don't have any cubox-i. I
could revert that commit, but it wouldn't be tested.

-michael

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