[net-next,0/2] Fix MTU warnings for fec/mv886xxx combo

Since changing the MTU of dsa slave interfaces was implemented, the
fec/mv88e6xxx combo has been giving warnings:

[    2.275925] mv88e6085 0.2:00: nonfatal error -95 setting MTU on port 9
[    2.284306] eth1: mtu greater than device maximum
[    2.287759] fec 400d1000.ethernet eth1: error -22 setting MTU to include DSA overhead

This patchset adds support for changing the MTU on mv88e6xxx switches,
which do support jumbo frames. And it modifies the FEC driver to
support its true MTU range, which is larger than the default Ethernet
MTU.

Andrew Lunn (2):
  net: dsa: mv88e6xxx: Implement MTU change
  net: fec: Set max MTU size to allow the MTU to be changed

 drivers/net/dsa/mv88e6xxx/chip.c          | 27 +++++++++++++++++++++++
 drivers/net/ethernet/freescale/fec_main.c |  2 ++
 2 files changed, 29 insertions(+)

On Sat, Jul 11, 2020 at 10:32:04PM +0200, Andrew Lunn wrote:
> Since changing the MTU of dsa slave interfaces was implemented, the
> fec/mv88e6xxx combo has been giving warnings:
> 
> [    2.275925] mv88e6085 0.2:00: nonfatal error -95 setting MTU on port 9
> [    2.284306] eth1: mtu greater than device maximum
> [    2.287759] fec 400d1000.ethernet eth1: error -22 setting MTU to include DSA overhead
> 
> This patchset adds support for changing the MTU on mv88e6xxx switches,
> which do support jumbo frames. And it modifies the FEC driver to
> support its true MTU range, which is larger than the default Ethernet
> MTU.

It's not just the fec/mv88e6xxx combo - I've been getting them on
Clearfog too.  It just hasn't been important enough to report yet.

On Sat, Jul 11, 2020 at 10:26:18PM +0100, Russell King - ARM Linux admin wrote:
> On Sat, Jul 11, 2020 at 10:32:04PM +0200, Andrew Lunn wrote:
> > Since changing the MTU of dsa slave interfaces was implemented, the
> > fec/mv88e6xxx combo has been giving warnings:
> > 
> > [    2.275925] mv88e6085 0.2:00: nonfatal error -95 setting MTU on port 9
> > [    2.284306] eth1: mtu greater than device maximum
> > [    2.287759] fec 400d1000.ethernet eth1: error -22 setting MTU to include DSA overhead
> > 
> > This patchset adds support for changing the MTU on mv88e6xxx switches,
> > which do support jumbo frames. And it modifies the FEC driver to
> > support its true MTU range, which is larger than the default Ethernet
> > MTU.
> 
> It's not just the fec/mv88e6xxx combo - I've been getting them on
> Clearfog too.  It just hasn't been important enough to report yet.

Hi Russell

That is the combination i have tested. mvneta has support for changing
its MTU. So this should stop the warnings on clearfog as well.

    Andrew

From: Andrew Lunn <andrew@lunn.ch>
Date: Sat, 11 Jul 2020 22:32:04 +0200

> Since changing the MTU of dsa slave interfaces was implemented, the
> fec/mv88e6xxx combo has been giving warnings:
> 
> [    2.275925] mv88e6085 0.2:00: nonfatal error -95 setting MTU on port 9
> [    2.284306] eth1: mtu greater than device maximum
> [    2.287759] fec 400d1000.ethernet eth1: error -22 setting MTU to include DSA overhead
> 
> This patchset adds support for changing the MTU on mv88e6xxx switches,
> which do support jumbo frames. And it modifies the FEC driver to
> support its true MTU range, which is larger than the default Ethernet
> MTU.

Series applied, thanks Andrew.