Re: [PATCH net-next v6 5/8] net: phy: Immediately call adjust_link if only tx_lpi_enabled changes

[Andrew Lunn <andrew@lunn.ch>]

On Tue, Feb 27, 2024 at 06:35:38AM +0100, Oleksij Rempel wrote:
> On Mon, Feb 26, 2024 at 07:59:28PM +0100, Andrew Lunn wrote:
> > On Mon, Feb 26, 2024 at 05:53:31PM +0000, Russell King (Oracle) wrote:
> > > On Mon, Feb 26, 2024 at 09:50:02AM -0800, Florian Fainelli wrote:
> > > > This is the source of the concern, we don't know which MAC drivers we might
> > > > end-up breaking by calling adjust_link(link == 1) twice in a row, hopefully
> > > > none, because they should be well written to only update the parameters that
> > > > need updating, but who knows?
> > > 
> > > Just quickly... There are some (I went through a bunch.) They don't
> > > support EEE. I haven't been through all though, so there could be
> > > some which support EEE and where adjust_link() with phydev->link=true
> > > twice in a row could result in badness.
> > 
> > So i think we all agree the MAC needs to see a down/up, even if the
> > link itself never went down. Anything else is too risky and will
> > probably break something somewhere.
> 
> Means, this patch should be dropped.

No.

This patch handles the case that EEE is changed, but does not require
an auto-neg cycle. If you drop this patch, that use case breaks.

You need to extend this patch to signal to the MAC a down followed by
an up. It is a fake down, the media side never goes down, but the MAC
needs to think it has in order to keep with the usual convention that
we never call adjust_link() twice with phydev->link not changing.

   Andrew