Re: [PATCH v12 2/2] arm: dts: aspeed: ventura: add Meta Ventura BMC

[Andrew Lunn <andrew@lunn.ch>]

On Wed, Apr 15, 2026 at 06:05:32PM +0800, P.K. Lee wrote:
> > > > > > If there are no devices on the bus, why enable it?
> > > > >
> > > > > We intentionally enable it so user-space tools can access the switch
> > > > > registers. I have added a comment in v13 to clarify this.
> > > >
> > > > Why would user space want to access the switch registers for an
> > > > unmanaged switch? It sounds like you are using Marvells SDK in
> > > > userspace to manage the switch, rather than using DSA.
> > > >
> > >
> > > We do have a custom user-space daemon that configures the switch
> > > registers for our specific use case. Should I remove the &mdio0 node
> > > if it is only enabled and has no other configuration in the upstream
> > > device tree?
> >
> > Please just be truthful that you have a user space driver, so need the
> > bus enabled.
> >
> > I also guess you have some other kernel code that allows you to
> > actually use the bus from user space? The typical ethernet IOCTL
> > handler does not work for you, since you don't have an ethernet device
> > using this bus. Such code is unlikely to be accepted into mainline. We
> > don't like user space drivers when there is a perfectly good kernel
> > driver for this switch.
> 
> Since the kernel driver for mv88e6xxx in kernel 6.6 used by this
> project does not support LED control, and this feature is only
> available starting from kernel 6.13, I had to initialize the LEDs of
> the 88E6393X from user space.
> 
> In this case, should I remove the &mdio0 node?

I would keep it, and add a comment why it is there. And upgrade the
kernel to 6.18, or backport the LED code.

     Andrew