Re: [PATCH net-next v6 2/7] net: phy: phylink: add helper to modify pause

[Andrew Lunn <andrew@lunn.ch>]

On Fri, Jul 10, 2026 at 12:05:06PM +0200, Maxime Chevallier wrote:
> Hi,
> 
> On 7/9/26 12:02, javen wrote:
> > From: Javen Xu <javen_xu@realsil.com.cn>
> > 
> > For Realtek nics, when we enable jumbo, pause are not supported. So we
> > must check the pause capabilities from ourself and lp.
> > 
> > Signed-off-by: Javen Xu <javen_xu@realsil.com.cn>
> > ---
> > Changes in v5:
> >  - no changes, new file
> > 
> > Changes in v6:
> >  - rename phylink_update_mac_pause_capabilities(), this function only
> >    changes mac pause capability
> >  - set asym pause and pause according to config->pause tx and rx
> >  - add phydev->lock when change pl->phydev->advertising
> > ---
> >  drivers/net/phy/phylink.c | 87 +++++++++++++++++++++++++++++++++++++++
> >  include/linux/phylink.h   |  2 +
> >  2 files changed, 89 insertions(+)
> > 
> > diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
> > index 59dfe35afa54..9e9cd79301d6 100644
> > --- a/drivers/net/phy/phylink.c
> > +++ b/drivers/net/phy/phylink.c
> > @@ -1828,6 +1828,93 @@ int phylink_set_fixed_link(struct phylink *pl,
> >  }
> >  EXPORT_SYMBOL_GPL(phylink_set_fixed_link);
> >  
> > +/**
> > + * phylink_update_mac_pause_capabilities() - Dynamically update MAC pause
> > + * @pl: a pointer to a &struct phylink returned from phylink_create()
> > + * @mac_pause: the new MAC pause capabilities mask
> > + *
> > + * This function allows a MAC driver to dynamically change its pause state,
> > + * such as losing/gaining Pause frame support based on MTU size.
> > + * It recalculates supported link modes and triggers renegotiation if needed.
> > + */
> > +void phylink_update_mac_pause_capabilities(struct phylink *pl, unsigned long mac_pause)
> > +{
> > +	struct phylink_link_state *config = &pl->link_config;
> > +	unsigned long old_pause, caps_added, caps_removed;
> > +	bool pause_adv, asym_adv;
> > +
> > +	ASSERT_RTNL();
> > +
> > +	if (mac_pause & ~(MAC_SYM_PAUSE | MAC_ASYM_PAUSE)) {
> > +		phylink_err(pl, "Attempted to dynamically change non-pause MAC capabilities\n");
> > +		return;
> > +	}
> > +
> > +	old_pause = pl->config->mac_capabilities & (MAC_SYM_PAUSE | MAC_ASYM_PAUSE);
> > +	caps_added = mac_pause & ~old_pause;
> > +	caps_removed = old_pause & ~mac_pause;
> > +
> > +	if (!caps_added && !caps_removed)
> > +		return;
> > +
> > +	mutex_lock(&pl->state_mutex);
> > +
> > +	pl->config->mac_capabilities &= ~(MAC_SYM_PAUSE | MAC_ASYM_PAUSE);
> > +	pl->config->mac_capabilities |= mac_pause;
> > +
> > +	if (caps_removed & MAC_SYM_PAUSE)
> > +		linkmode_clear_bit(ETHTOOL_LINK_MODE_Pause_BIT, pl->supported);
> > +	if (caps_removed & MAC_ASYM_PAUSE)
> > +		linkmode_clear_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT, pl->supported);
> > +
> > +	linkmode_and(config->advertising, config->advertising, pl->supported);
> > +
> > +	if (caps_added & MAC_SYM_PAUSE) {
> > +		linkmode_set_bit(ETHTOOL_LINK_MODE_Pause_BIT, pl->supported);
> > +		if (pl->phydev && !phylink_test(pl->phydev->supported, Pause))
> > +			linkmode_clear_bit(ETHTOOL_LINK_MODE_Pause_BIT, pl->supported);
> 
> Why look at what the PHY can do here ? You shouldn't need to.

I question the whole idea here. Why is this so complex? phylink should
already have all the needed code, once you change
pl->config->mac_capabilities you just need to call that code. Yes, it
might need refactoring into a helper, but that would be a preparatory
patch.

Once you start reusing existing code, i then wounder if it is just as
simple to allow any of the mac_capabilities to be changed, not just
pause?

	Andrew