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Message-Id: <1209567842.16926.27.camel@gentoo-jocke.transmode.se>
Date: Wed, 30 Apr 2008 17:04:02 +0200
From: Joakim Tjernlund <joakim.tjernlund@...nsmode.se>
To: Grant Likely <grant.likely@...retlab.ca>
Cc: wg@...ndegger.com, linuxppc-dev@...abs.org, paulus@...ba.org,
netdev@...r.kernel.org, Wolfgang Denk <wd@...x.de>
Subject: Re: [PATCH] [POWERPC] mpc5200: Allow for fixed speed MII
configurations
On Wed, 2008-04-30 at 08:28 -0600, Grant Likely wrote:
> On Wed, Apr 30, 2008 at 8:16 AM, Joakim Tjernlund
> <joakim.tjernlund@...nsmode.se> wrote:
> >
> >
> > On Wed, 2008-04-30 at 07:26 -0600, Grant Likely wrote:
> > > On Wed, Apr 30, 2008 at 7:10 AM, Joakim Tjernlund
> > > <joakim.tjernlund@...nsmode.se> wrote:
> > > >
> > > >
> > > > On Wed, 2008-04-30 at 07:07 -0600, Grant Likely wrote:
> > > > > On Wed, Apr 30, 2008 at 1:36 AM, Joakim Tjernlund
> > > > > <joakim.tjernlund@...nsmode.se> wrote:
> > > > > >
> > > > > > On Tue, 2008-04-29 at 17:06 -0600, Grant Likely wrote:
> > > > > > > From: Grant Likely <grant.likely@...retlab.ca>
> > > > > > >
> > > > > > > Various improvements for configuring the MPC5200 MII link from the
> > > > > > > device tree:
> > > > > > > * Look for 'current-speed' property for fixed speed MII links
> > > > > >
> > > > > > Not that I have looked, but why can't you use the fixed-link property?
> > > > >
> > > > > fixed-link seems to be a recent invention, whereas current-speed is
> > > > > better know having already been in use with serial devices. It seemed
> > > > > to me to be a better choice, but my opinion can probably be swayed
> > > > > (arguments welcome).
> > > >
> > > > yes it is fairly new. You get alot more than just speed: Duplex/Pause
> > > > You need these too.
> > >
> > > duplex I've got. pause I don't need.
> >
> > dunno how you speify Half/Full Duplex, but isn't it possible that
> > someone else wants to use Pause in the future?
> > Isn't the point that everyone should use fixed-link when it is there
> > for this purpose?
>
> The format of the data is pretty much entirely device dependent (much
> like interrupt and gpio specifiers are controller dependent). I see
> any need in trying to define a common format for this data since it is
> entirely local to the device. ie. there is requirement for this data
> to be in the same format for every device. Also, by not trying to
> lock it down into a common format it gives future devices freedom to
> specify additional flags and parameters in the data.
>
> so,
> * gianfar: needs 5 bits of data.
> * 5200 FEC: only needs 2.
>
> As for 'current-speed' vs. 'fixed-link'. I just think 'current-speed'
> is the better name. :-)
Then some day someone else needs Pause or need to control Duplex. Then
you end up with several impl. Maybe fixed-link isn't the best
name, but it is designed for this purpose.
Anyhow, I not going to argue this more. Seems like I am the
only one thinking it would be better to use fixed-link instead so I
guess I am wrong here.
Jocke
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