On Fri, Jul 10, 2026 at 12:05:06PM +0200, Maxime Chevallier wrote:

Hi,

On 7/9/26 12:02, javen wrote:

quoted

From: Javen Xu <redacted>

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 <redacted>
---
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