Re: [PATCH net-next v2 1/8] net: phylink: propagate resolved link config via mac_link_up() - Russell King

From: Russell King - ARM Linux admin <linux@armlinux•org.uk>
To: Vladimir Oltean <olteanv@gmail•com>
Cc: Andrew Lunn <andrew@lunn•ch>,
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Subject: Re: [PATCH net-next v2 1/8] net: phylink: propagate resolved link config via mac_link_up()
Date: Wed, 26 Feb 2020 18:25:06 +0000	[thread overview]
Message-ID: <20200226182506.GG25745@shell.armlinux.org.uk> (raw)
In-Reply-To: <CA+h21hpzCY=+0U4JgFbqGLS=Sh6SjkSt=4J9e0AGVHKJPOHq1A@mail.gmail.com>

On Wed, Feb 26, 2020 at 08:22:39PM +0200, Vladimir Oltean wrote:
> On Wed, 26 Feb 2020 at 20:21, Vladimir Oltean <olteanv@gmail•com> wrote:
> >
> > On Wed, 26 Feb 2020 at 15:36, Russell King - ARM Linux admin
> > <linux@armlinux•org.uk> wrote:
> > >
> > >
> > > dpaa2 is complicated by the firmware, and that we can't switch the
> > > interface mode between (SGMII,1000base-X) and 10G.
> > >
> > > If the firmware is in "DPMAC_LINK_TYPE_PHY" mode, it expects to be told
> > > the current link parameters via the dpmac_set_link_state() call - it
> > > isn't clear whether that needs to be called for other modes with the
> > > up/down state (firmware API documentation is poor.)
> > >
> >
> > With PCS control in Linux, I am pretty sure that you don't want
> > anything other than DPMAC_LINK_TYPE_PHY anyway.
> > Basically in DPMAC_LINK_TYPE_FIXED, the MC firmware is in control of
> > the PCS and polls its link state to emit link notifications to objects
> > connected to the DPMAC. So Linux control of PCS would class with
> 
> s/class/clash/
> 
> > firmware control of the PCS, leading to undesirable side-effects to
> > say the least.

Yes, which is why we only register the PCS with phylink if we're in
DPMAC_LINK_TYPE_PHY mode.

-- 
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