Using ethtool or swconfig to change link settings for mt7620a?

From: Daniel Santos <daniel.santos@pobox.com>
To: Felix Fietkau <nbd@nbd.name>,
	openwrt-devel <openwrt-devel@lists.openwrt.org>
Cc: netdev@vger.kernel.org, Vitaly Chekryzhev <13hakta@gmail.com>
Subject: Using ethtool or swconfig to change link settings for mt7620a?
Date: Sat, 8 Jun 2019 04:06:54 -0500	[thread overview]
Message-ID: <5316c6da-1966-4896-6f4d-8120d9f1ff6e@pobox.com> (raw)

Hello,

I need to change auto-negotiate, speed and duplex for a port on my
mt7620a-based device, but I'm not quite certain that I understand the
structure here.  When using ethtool on eth0 I always get ENODEV,
apparently because priv->phy_dev is always NULL in fe_get_link_ksettings
of drivers/net/ethernet/mtk/ethtool.c.  But I'm being told that eth0 is
only an internal device between the µC and the switch hardware, so it
isn't even the one I need to change.

If this is true, then it looks like I will need to implement a
get_port_link function for struct switch_dev_ops?  Can anybody confirm
this to be the case?  Also, are there any examples aside from the
Broadcom drivers?  I have the mt7620 programmer's guide and it specifies
the registers I need to change.

Thanks,
Daniel