On Mon, Jul 20, 2020 at 01:02:21PM +0000, Ioana Ciornei wrote:

On 7/20/20 3:44 PM, Russell King - ARM Linux admin wrote:

quoted

On Mon, Jul 20, 2020 at 11:40:44AM +0000, Ioana Ciornei wrote:

quoted

On 6/30/20 5:29 PM, Russell King wrote:

quoted

With PCS support, how we implement interface reconfiguration is not up
to the job; we end up reconfiguring the PCS for an interface change
while the link could potentially be up.  In order to solve this, add
two additional MAC methods for interface configuration, one to prepare
for the change, and one to finish the change.

This allows mvneta and mvpp2 to shutdown what they require prior to the
MAC and PCS configuration calls, and then restart as appropriate.

This impacts ksettings_set(), which now needs to identify whether the
change is a minor tweak to the advertisement masks or whether the
interface mode has changed, and call the appropriate function for that
update.

Signed-off-by: Russell King <redacted>
---
   drivers/net/phy/phylink.c | 80 ++++++++++++++++++++++++++-------------
   include/linux/phylink.h   | 48 +++++++++++++++++++++++
   2 files changed, 102 insertions(+), 26 deletions(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 09f4aeef15c7..a31a00fb4974 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c

@@ -433,23 +433,47 @@ static void phylink_mac_pcs_an_restart(struct phylink *pl)
   	}
   }
   
-static void phylink_pcs_config(struct phylink *pl, bool force_restart,
-			       const struct phylink_link_state *state)
+static void phylink_change_interface(struct phylink *pl, bool restart,
+				     const struct phylink_link_state *state)
   {
-	bool restart = force_restart;
+	int err;
+
+	phylink_dbg(pl, "change interface %s\n", phy_modes(state->interface));
   
-	if (pl->pcs_ops && pl->pcs_ops->pcs_config(pl->config,
-						   pl->cur_link_an_mode,
-						   state->interface,
-						   state->advertising,
-						   !!(pl->link_config.pause &
-						      MLO_PAUSE_AN)))
-		restart = true;
+	if (pl->mac_ops->mac_prepare) {
+		err = pl->mac_ops->mac_prepare(pl->config, pl->cur_link_an_mode,
+					       state->interface);
+		if (err < 0) {
+			phylink_err(pl, "mac_prepare failed: %pe\n",
+				    ERR_PTR(err));
+			return;
+		}
+	}
   
   	phylink_mac_config(pl, state);
   
+	if (pl->pcs_ops) {
+		err = pl->pcs_ops->pcs_config(pl->config, pl->cur_link_an_mode,
+					      state->interface,
+					      state->advertising,
+					      !!(pl->link_config.pause &
+						 MLO_PAUSE_AN));
+		if (err < 0)
+			phylink_err(pl, "pcs_config failed: %pe\n",
+				    ERR_PTR(err));
+		if (err > 0)
+			restart = true;
+	}
   	if (restart)
   		phylink_mac_pcs_an_restart(pl);
+
+	if (pl->mac_ops->mac_finish) {
+		err = pl->mac_ops->mac_finish(pl->config, pl->cur_link_an_mode,
+					      state->interface);
+		if (err < 0)
+			phylink_err(pl, "mac_prepare failed: %pe\n",
+				    ERR_PTR(err));
+	}
   }
   
   /*

@@ -555,7 +579,7 @@ static void phylink_mac_initial_config(struct phylink *pl, bool force_restart)
   	link_state.link = false;
   
   	phylink_apply_manual_flow(pl, &link_state);
-	phylink_pcs_config(pl, force_restart, &link_state);
+	phylink_change_interface(pl, force_restart, &link_state);
   }
   
   static const char *phylink_pause_to_str(int pause)

@@ -674,7 +698,7 @@ static void phylink_resolve(struct work_struct *w)
   				phylink_link_down(pl);
   				cur_link_state = false;
   			}
-			phylink_pcs_config(pl, false, &link_state);
+			phylink_change_interface(pl, false, &link_state);
   			pl->link_config.interface = link_state.interface;
   		} else if (!pl->pcs_ops) {
   			/* The interface remains unchanged, only the speed,

@@ -1450,22 +1474,26 @@ int phylink_ethtool_ksettings_set(struct phylink *pl,
   		return -EINVAL;
   
   	mutex_lock(&pl->state_mutex);
-	linkmode_copy(pl->link_config.advertising, config.advertising);
-	pl->link_config.interface = config.interface;
   	pl->link_config.speed = config.speed;
   	pl->link_config.duplex = config.duplex;
-	pl->link_config.an_enabled = kset->base.autoneg !=
-				     AUTONEG_DISABLE;
-
-	if (pl->cur_link_an_mode == MLO_AN_INBAND &&
-	    !test_bit(PHYLINK_DISABLE_STOPPED, &pl->phylink_disable_state)) {
-		/* If in 802.3z mode, this updates the advertisement.
-		 *
-		 * If we are in SGMII mode without a PHY, there is no
-		 * advertisement; the only thing we have is the pause
-		 * modes which can only come from a PHY.
-		 */
-		phylink_pcs_config(pl, true, &pl->link_config);
+	pl->link_config.an_enabled = kset->base.autoneg != AUTONEG_DISABLE;
+
+	if (pl->link_config.interface != config.interface) {

I cannot seem to understand where in this function config.interface
could become different from pl->link_config.interface.

Is there something obvious that I am missing?

The validate() method is free to change the interface if required -
there's a helper that MACs can use to achieve that for switching
between 1000base-X and 2500base-X.  Useful if you have a FC SFP
plugged in capable of 2500base-X, but want to communicate with a
1000base-X link partner.

Ok, I was not aware of this possibility. Now that I looked, it's even 
documented in phylink's header file.

My confusion stems from the fact that I expected this to come from the 
SFP itself requesting an interface type or the other. So the usage here 
is to know what is at the other end of the line and configure the 
appropriate advertisement with ethtool?

SFPs do not specify their host interface - they specify a range of
parameters which describe the media side.  Even then, it is not
unusual for various parameters in the EEPROM to be incorrect.

Also, 2500BASE-X at one end and 1000BASE-X at the other end is not
compatible - you won't even get synchronisation between the two ends,
so there's no possibility for passing any data about capabilities.

The idea is that if you have a module that can support 2500BASE-X and
1000BASE-X (such as a fibrechannel SFP) then, rather than being solidly
tied by the kernel to one or other of the speeds, you can request the
kernel use the other speed via ethtool - and switching between the two
requires changing the phy_interface_t setting.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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