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Date:      Sat, 11 Feb 2012 21:59:08 -0700
From:      Warner Losh <imp@bsdimp.com>
To:        Adrian Chadd <adrian@freebsd.org>
Cc:        Aleksandr Rybalko <ray@ddteam.net>, Stefan Bethke <stb@lassitu.de>, Juli Mallett <jmallett@freebsd.org>, FreeBSD-arch <freebsd-arch@freebsd.org>, Aleksandr Rybalko <ray@freebsd.org>, Marius Strobl <marius@alchemy.franken.de>
Subject:   Re: Extending sys/dev/mii
Message-ID:  <58EA57DC-75DF-4813-BB03-FD27F2A49BA2@bsdimp.com>
In-Reply-To: <CAJ-Vmon=cPivcJjb_dvuMzsok2Qp-MeNLK0uNo5g8O2ekEaOMA@mail.gmail.com>
References:  <95372FB3-406F-46C2-8684-4FDB672D9FCF@lassitu.de> <20120106214741.GB88161@alchemy.franken.de> <F60B2B70-049F-4497-BBA8-3C421088C1EA@lassitu.de> <20120108130039.GG88161@alchemy.franken.de> <23477898-8D85-498C-8E30-192810BD68A8@lassitu.de> <20120111193738.GB44286@alchemy.franken.de> <66DDA0A2-F878-43FF-8824-54868F493B18@lassitu.de> <20120125221753.GA17821@alchemy.franken.de> <AF2CF7A4-27B8-4181-96F5-7998B126CD1C@lassitu.de> <CAJ-VmomcgC6V-sY7jN%2Bh6T7uPfVesPBV%2BKPu2TVD4YDKrdk4LQ@mail.gmail.com> <20120211111731.GE39861@alchemy.franken.de> <20120211144544.c91701d9.ray@ddteam.net> <CAJ-Vmo=CLMcO%2BR21TVKC3zVGS4rHO2Ca31D9ts2kNwpnhAtOvQ@mail.gmail.com> <B1700D0A-240D-4274-AA3F-FCA798AD2F14@bsdimp.com> <CAJ-Vmon=cPivcJjb_dvuMzsok2Qp-MeNLK0uNo5g8O2ekEaOMA@mail.gmail.com>

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On Feb 11, 2012, at 9:49 PM, Adrian Chadd wrote:

> On 11 February 2012 17:15, Warner Losh <imp@bsdimp.com> wrote:
>>=20
>> On Feb 11, 2012, at 6:00 PM, Adrian Chadd wrote:
>>> I'd like to try and finally bring some sanity to the hardcoded PHY
>>> mask handling in if_arge (and make it actually work for AR71xx and
>>> AR724x - where AR71xx has one shared MDIO bus between both MACs, but
>>> AR724x has two independent MDIO busses..)
>>=20
>> FDT would do that...
>=20
> .. how would it bring sanity to the device driver?

FDT would encode the links between the MAC and the PHY.  FDT is a =
directed graph, not a tree, so you can have multiple paths to a device =
node that follow different domains.

> Right now the driver assumes that both arge0 and arge1 mdiobus are the
> same and uses the phymask setting to determine how/when to access
> registers (ie, trying to read/write from phy registers not in the
> phymask of argeX are denied.) It is one of the annoying issues with
> the AR7241 internal switch support as that switch hangs off of arge1's
> MII bus.

It would no longer need to do this, or make any assumptions at all.  FDT =
would tell it all.

> It may make it easier to specify the configuration but it doesn't fix
> the fundamentally wrong assumption.

Nope.  Bad assumptions would still need to be fixed.

> The trouble in this whole mess (where FDT may help) is that phy's for
> arge0 may actually sit on arge1. So you can't probe/attach the miibus
> on arge0 until you've probe/attached arge1, so the arge1 MII registers
> can be tickled.

The PHYs don't sit on arge1.  They sit on another device that the driver =
bogusly assumes is tightly coupled to arge1, when in fact it isn't.

> Ray/Stefan/others: if anything, I'd like to try and bring sanity to
> this particular thorny issue in -HEAD before we worry about switch PHY
> devices.

Warner




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