On 2023-10-16 17:45, Andrew Lunn wrote:
On Mon, Oct 16, 2023 at 05:36:24PM +0200, Rafał Miłecki wrote:
On 2023-10-14 18:50, Andrew Lunn wrote:
> On Fri, Oct 13, 2023 at 12:33:14PM +0200, Rafał Miłecki wrote:
> > From: Rafał Miłecki <rafal@xxxxxxxxxx>
> >
> > While switch ports 5 and 7 are disabled (vendor designed port 8 to be
> > used for CPU traffic) they could be used strictly technically. For
> > some
> > reason however both those ports need forcing link to be usable.
>
> This explanation is not making much sense to me.
>
> I assume this board does not have an RJ45 for these two ports? But
> does it have a header so you can access the MII interface?
This PATCH as it is requires a basic familiarity with Northstar
platform
or checking bcm-ns.dtsi.
All Northstar (BCM5301X) devices have 3 Ethernet interfaces. 99% of
them
have:
1. gmac0 connected to port 5
2. gmac1 connected to port 7
3. gmac2 connected to port 8
(it's described in bcm-ns.dtsi).
Some vendors decide to use gmac0 and switch port 5. They fill NVRAM
with
MAC for gmac0.
Some vendors decide to use gmac2 & port 8. They set MAC for gmac2.
Netgear decided to use gmac2 & port 8 for R8000. They fill NVRAM with
MAC for gmac2.
If you however insist on using gmac0 you could do that. That just
requires setting up gmac0 with a custom/random MAC and forcing link
for
switch ports as described in this PATCH.
If the ports are not used, you have them set to disabled, why do they
need a fixed-link? That is what i don't understand yet.
So developers/hackers can use them for custom needs by just dropping
"disabled" bit. That's a pretty simple step compared to figuring out
that a fixed link is needed.
I can imagine advanced users using extra ports and interfaces to get
higher speeds. If you use a single switch port and single interface
you're limited to 1 Gbps. By using two you can exceed that limitation.
This is clearly some corner case but I don't think it really violates
what DT is for. We just describe hardware more clearly. There is a fixed
link after all. That port just happens to be disabled.
--
Rafał Miłecki
