Subject: Re: [RFC PATCH 10/10] net: stmmac: dwmac-loongson: Add GNET support

From: "Russell King (Oracle)" <[email-masked]>
Date: Fri, 14 Jul 2023 09:45:07 +0100

On Fri, Jul 14, 2023 at 10:24:37AM +0800, Feiyang Chen wrote:
> On Thu, Jul 13, 2023 at 12:07 PM Andrew Lunn <[email-masked]> wrote:
> >
> > On Thu, Jul 13, 2023 at 10:49:38AM +0800, Feiyang Chen wrote:
> > > Add GNET support. Use the fix_mac_speed() callback to workaround
> > > issues with the Loongson PHY.
> >
> > What are the issues?
> >
> 
> Hi, Andrew,
> 
> There is an issue with the synchronization between the network card
> and the PHY. In the case of gigabit operation, if the PHY's speed
> changes, the network card's speed remains unaffected. Hence, it is
> necessary to initiate a re-negotiation process with the PHY to align
> the link speeds properly.

Please could you explain a bit more what happens when "the PHY's speed
changes". Are you suggesting that:

You have a connection where the media side has negotiated 1G speed.
The gigabit partner is disconnected, so the link goes down, and is then
replaced by a partner only capable of 100M. The link comes back up at
100M, but the network card continues trying to operate at 1G?

Thanks.

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