Subject: Re: [RFC PATCH v2 5/8] net: pcs: add driver for MediaTek USXGMII PCS

From: "Russell King (Oracle)" <[email-masked]>
Date: Wed, 6 Dec 2023 17:58:08 +0000

On Wed, Dec 06, 2023 at 10:58:38AM +0100, Maxime Chevallier wrote:
> On Wed, 6 Dec 2023 01:44:38 +0000
> Daniel Golle <[email-masked]> wrote:
> > +	/* Read USXGMII link status */
> > +	state->link = FIELD_GET(RG_PCS_RX_LINK_STATUS,
> > +				mtk_r32(mpcs, RG_PCS_RX_STATUS0));
> > +
> > +	/* Continuously repeat re-configuration sequence until link comes up */
> > +	if (!state->link) {
> > +		mtk_usxgmii_pcs_config(pcs, mpcs->neg_mode,
> > +				       state->interface, NULL, false);
> > +		return;
> 
> .pcs_get_state() isn't called only for link state polling,but also when querying
> the link state from ethtool, from phylink_ethtool_ksettings_get().
> 
> As mtk_usxgmii_pcs_config triggers a pcs reset and reconfiguration, won't this disrupt
> the link ? 

Highly likely if there's a race, but note that mtk_usxgmii_pcs_config()
only gets called if the link is *down*. I guess some IPs need a bit of
kicking to work properly.

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