Broken ethernet on SolidRun cubox-i

[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.

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.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!