[PATCH net-next 0/7] net: phylink: add PCS validation

[PATCH net-next 0/7] net: phylink: add PCS validation

[Russell King (Oracle)]

Hi,

This series allows phylink to include the PCS in its validation step.
There are two reasons to make this change:

1. Some of the network drivers that are making use of the split PCS
   support are already manually calling into their PCS drivers to
   perform validation. E.g. stmmac with xpcs.

2. Logically, some network drivers such as mvneta and mvpp2, the
   restriction we impose in the validate() callback is a property of
   the "PCS" block that we provide rather than the MAC.

This series:

1. Gives phylink a mechanism to query the MAC driver which PCS is
   wishes to use for the PHY interface mode. This is necessary to allow
   the PCS to be involved in the validation step without making changes
   to the configuration.

2. Provide a pcs_validate() method that PCS can implement. This follows
   a similar model to the MAC's validate() callback, but with some minor
   differences due to observations from the various implementations.
   E.g. returning an error code for not-supported and the way the
   advertising bitmap is masked.

3. Convert mvpp2 and mvneta to this as examples of its use. Further
   Conversions are in the pipeline, including for stmmac+xpcs, as well
   as some DSA drivers. Note that DSA conversion to this is conditional
   upon all DSA drivers populating their supported_interfaces bitmap,
   since this is required before mac_select_pcs() can be used.

Existing drivers that set a PCS in mac_prepare() or mac_config(), or
shortly after phylink_create() will continue to work. However, it should
be noted that mac_select_pcs() will be called during phylink_create(),
and thus any PCS returned by mac_select_pcs() must be available by this
time - or we drop the check in phylink_create().

 drivers/net/ethernet/marvell/mvneta.c           | 229 ++++++++++++++++--------
 drivers/net/ethernet/marvell/mvpp2/mvpp2.h      |   3 +-
 drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 112 ++++++------
 drivers/net/phy/phylink.c                       |  99 +++++++++-
 include/linux/phylink.h                         |  38 ++++
 5 files changed, 337 insertions(+), 144 deletions(-)

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

[PATCH net-next 1/7] net: phylink: add mac_select_pcs() method to phylink_mac_ops

[Russell King (Oracle)]

mac_select_pcs() allows us to have an explicit point to query which
PCS the MAC wishes to use for a particular PHY interface mode, thereby
allowing us to add support to validate the link settings with the PCS.

Phylink will also use this to select the PCS to be used during a major
configuration event without the MAC driver needing to call
phylink_set_pcs().

Note that if mac_select_pcs() is present, the supported_interfaces
bitmap must be filled in; this avoids mac_select_pcs() being called
with PHY_INTERFACE_MODE_NA when we want to get support for all
interface types. Phylink will return an error in phylink_create()
unless this condition is satisfied.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 drivers/net/phy/phylink.c | 68 +++++++++++++++++++++++++++++++++------
 include/linux/phylink.h   | 18 +++++++++++
 2 files changed, 77 insertions(+), 9 deletions(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 20df8af3e201..c7035d65e159 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -419,6 +419,23 @@ void phylink_generic_validate(struct phylink_config *config,
 }
 EXPORT_SYMBOL_GPL(phylink_generic_validate);
 
+static int phylink_validate_mac_and_pcs(struct phylink *pl,
+					unsigned long *supported,
+					struct phylink_link_state *state)
+{
+	struct phylink_pcs *pcs;
+
+	if (pl->mac_ops->mac_select_pcs) {
+		pcs = pl->mac_ops->mac_select_pcs(pl->config, state->interface);
+		if (IS_ERR(pcs))
+			return PTR_ERR(pcs);
+	}
+
+	pl->mac_ops->validate(pl->config, supported, state);
+
+	return phylink_is_empty_linkmode(supported) ? -EINVAL : 0;
+}
+
 static int phylink_validate_any(struct phylink *pl, unsigned long *supported,
 				struct phylink_link_state *state)
 {
@@ -434,9 +451,10 @@ static int phylink_validate_any(struct phylink *pl, unsigned long *supported,
 
 			t = *state;
 			t.interface = intf;
-			pl->mac_ops->validate(pl->config, s, &t);
-			linkmode_or(all_s, all_s, s);
-			linkmode_or(all_adv, all_adv, t.advertising);
+			if (!phylink_validate_mac_and_pcs(pl, s, &t)) {
+				linkmode_or(all_s, all_s, s);
+				linkmode_or(all_adv, all_adv, t.advertising);
+			}
 		}
 	}
 
@@ -458,9 +476,7 @@ static int phylink_validate(struct phylink *pl, unsigned long *supported,
 			return -EINVAL;
 	}
 
-	pl->mac_ops->validate(pl->config, supported, state);
-
-	return phylink_is_empty_linkmode(supported) ? -EINVAL : 0;
+	return phylink_validate_mac_and_pcs(pl, supported, state);
 }
 
 static int phylink_parse_fixedlink(struct phylink *pl,
@@ -750,10 +766,21 @@ static void phylink_mac_pcs_an_restart(struct phylink *pl)
 static void phylink_major_config(struct phylink *pl, bool restart,
 				  const struct phylink_link_state *state)
 {
+	struct phylink_pcs *pcs = NULL;
 	int err;
 
 	phylink_dbg(pl, "major config %s\n", phy_modes(state->interface));
 
+	if (pl->mac_ops->mac_select_pcs) {
+		pcs = pl->mac_ops->mac_select_pcs(pl->config, state->interface);
+		if (IS_ERR(pcs)) {
+			phylink_err(pl,
+				    "mac_select_pcs unexpectedly failed: %pe\n",
+				    pcs);
+			return;
+		}
+	}
+
 	if (pl->mac_ops->mac_prepare) {
 		err = pl->mac_ops->mac_prepare(pl->config, pl->cur_link_an_mode,
 					       state->interface);
@@ -764,6 +791,12 @@ static void phylink_major_config(struct phylink *pl, bool restart,
 		}
 	}
 
+	/* If we have a new PCS, switch to the new PCS after preparing the MAC
+	 * for the change.
+	 */
+	if (pcs)
+		phylink_set_pcs(pl, pcs);
+
 	phylink_mac_config(pl, state);
 
 	if (pl->pcs_ops) {
@@ -1155,6 +1188,14 @@ struct phylink *phylink_create(struct phylink_config *config,
 	struct phylink *pl;
 	int ret;
 
+	/* Validate the supplied configuration */
+	if (mac_ops->mac_select_pcs &&
+	    phy_interface_empty(config->supported_interfaces)) {
+		dev_err(config->dev,
+			"phylink: error: empty supported_interfaces but mac_select_pcs() method present\n");
+		return ERR_PTR(-EINVAL);
+	}
+
 	pl = kzalloc(sizeof(*pl), GFP_KERNEL);
 	if (!pl)
 		return ERR_PTR(-ENOMEM);
@@ -1222,9 +1263,10 @@ EXPORT_SYMBOL_GPL(phylink_create);
  * @pl: a pointer to a &struct phylink returned from phylink_create()
  * @pcs: a pointer to the &struct phylink_pcs
  *
- * Bind the MAC PCS to phylink.  This may be called after phylink_create(),
- * in mac_prepare() or mac_config() methods if it is desired to dynamically
- * change the PCS.
+ * Bind the MAC PCS to phylink.  This may be called after phylink_create().
+ * If it is desired to dynamically change the PCS, then the preferred method
+ * is to use mac_select_pcs(), but it may also be called in mac_prepare()
+ * or mac_config().
  *
  * Please note that there are behavioural changes with the mac_config()
  * callback if a PCS is present (denoting a newer setup) so removing a PCS
@@ -1235,6 +1277,14 @@ void phylink_set_pcs(struct phylink *pl, struct phylink_pcs *pcs)
 {
 	pl->pcs = pcs;
 	pl->pcs_ops = pcs->ops;
+
+	if (!pl->phylink_disable_state &&
+	    pl->cfg_link_an_mode == MLO_AN_INBAND) {
+		if (pl->config->pcs_poll || pcs->poll)
+			mod_timer(&pl->link_poll, jiffies + HZ);
+		else
+			del_timer(&pl->link_poll);
+	}
 }
 EXPORT_SYMBOL_GPL(phylink_set_pcs);
 
diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index a2f266cc3442..f44b33cddc4d 100644
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -112,6 +112,7 @@ struct phylink_config {
 /**
  * struct phylink_mac_ops - MAC operations structure.
  * @validate: Validate and update the link configuration.
+ * @mac_select_pcs: Select a PCS for the interface mode.
  * @mac_pcs_get_state: Read the current link state from the hardware.
  * @mac_prepare: prepare for a major reconfiguration of the interface.
  * @mac_config: configure the MAC for the selected mode and state.
@@ -126,6 +127,8 @@ struct phylink_mac_ops {
 	void (*validate)(struct phylink_config *config,
 			 unsigned long *supported,
 			 struct phylink_link_state *state);
+	struct phylink_pcs *(*mac_select_pcs)(struct phylink_config *config,
+					      phy_interface_t interface);
 	void (*mac_pcs_get_state)(struct phylink_config *config,
 				  struct phylink_link_state *state);
 	int (*mac_prepare)(struct phylink_config *config, unsigned int mode,
@@ -178,6 +181,21 @@ struct phylink_mac_ops {
  */
 void validate(struct phylink_config *config, unsigned long *supported,
 	      struct phylink_link_state *state);
+/**
+ * @mac_select_pcs: Select a PCS for the interface mode.
+ * @config: a pointer to a &struct phylink_config.
+ * @interface: PHY interface mode for PCS
+ *
+ * Return the &struct phylink_pcs for the specified interface mode, or
+ * NULL if none is required, or an error pointer on error.
+ *
+ * This must not modify any state. It is used to query which PCS should
+ * be used. Phylink will use this during validation to ensure that the
+ * configuration is valid, and when setting a configuration to internally
+ * set the PCS that will be used.
+ */
+struct phylink_pcs *mac_select_pcs(struct phylink_config *config,
+				   phy_interface_t interface);
 
 /**
  * mac_pcs_get_state() - Read the current inband link state from the hardware
-- 
2.30.2

[PATCH net-next 2/7] net: phylink: add pcs_validate() method

[Russell King (Oracle)]

Add a hook for PCS to validate the link parameters. This avoids MAC
drivers having to have knowledge of their PCS in their validate()
method, thereby allowing several MAC drivers to be simplfied.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 drivers/net/phy/phylink.c | 31 +++++++++++++++++++++++++++++++
 include/linux/phylink.h   | 20 ++++++++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index c7035d65e159..420201858564 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -424,13 +424,44 @@ static int phylink_validate_mac_and_pcs(struct phylink *pl,
 					struct phylink_link_state *state)
 {
 	struct phylink_pcs *pcs;
+	int ret;
 
+	/* Get the PCS for this interface mode */
 	if (pl->mac_ops->mac_select_pcs) {
 		pcs = pl->mac_ops->mac_select_pcs(pl->config, state->interface);
 		if (IS_ERR(pcs))
 			return PTR_ERR(pcs);
+	} else {
+		pcs = pl->pcs;
+	}
+
+	if (pcs) {
+		/* The PCS, if present, must be setup before phylink_create()
+		 * has been called. If the ops is not initialised, print an
+		 * error and backtrace rather than oopsing the kernel.
+		 */
+		if (!pcs->ops) {
+			phylink_err(pl, "interface %s: uninitialised PCS\n",
+				    phy_modes(state->interface));
+			dump_stack();
+			return -EINVAL;
+		}
+
+		/* Validate the link parameters with the PCS */
+		if (pcs->ops->pcs_validate) {
+			ret = pcs->ops->pcs_validate(pcs, supported, state);
+			if (ret < 0 || phylink_is_empty_linkmode(supported))
+				return -EINVAL;
+
+			/* Ensure the advertising mask is a subset of the
+			 * supported mask.
+			 */
+			linkmode_and(state->advertising, state->advertising,
+				     supported);
+		}
 	}
 
+	/* Then validate the link parameters with the MAC */
 	pl->mac_ops->validate(pl->config, supported, state);
 
 	return phylink_is_empty_linkmode(supported) ? -EINVAL : 0;
diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index f44b33cddc4d..381edda618d8 100644
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -416,6 +416,7 @@ struct phylink_pcs {
 
 /**
  * struct phylink_pcs_ops - MAC PCS operations structure.
+ * @pcs_validate: validate the link configuration.
  * @pcs_get_state: read the current MAC PCS link state from the hardware.
  * @pcs_config: configure the MAC PCS for the selected mode and state.
  * @pcs_an_restart: restart 802.3z BaseX autonegotiation.
@@ -423,6 +424,8 @@ struct phylink_pcs {
  *               (where necessary).
  */
 struct phylink_pcs_ops {
+	int (*pcs_validate)(struct phylink_pcs *pcs, unsigned long *supported,
+			    const struct phylink_link_state *state);
 	void (*pcs_get_state)(struct phylink_pcs *pcs,
 			      struct phylink_link_state *state);
 	int (*pcs_config)(struct phylink_pcs *pcs, unsigned int mode,
@@ -435,6 +438,23 @@ struct phylink_pcs_ops {
 };
 
 #if 0 /* For kernel-doc purposes only. */
+/**
+ * pcs_validate() - validate the link configuration.
+ * @pcs: a pointer to a &struct phylink_pcs.
+ * @supported: ethtool bitmask for supported link modes.
+ * @state: a const pointer to a &struct phylink_link_state.
+ *
+ * Validate the interface mode, and advertising's autoneg bit, removing any
+ * media ethtool link modes that would not be supportable from the supported
+ * mask. Phylink will propagate the changes to the advertising mask. See the
+ * &struct phylink_mac_ops validate() method.
+ *
+ * Returns -EINVAL if the interface mode/autoneg mode is not supported.
+ * Returns non-zero positive if the link state can be supported.
+ */
+int pcs_validate(struct phylink_pcs *pcs, unsigned long *supported,
+		 const struct phylink_link_state *state);
+
 /**
  * pcs_get_state() - Read the current inband link state from the hardware
  * @pcs: a pointer to a &struct phylink_pcs.
-- 
2.30.2

[PATCH net-next 3/7] net: mvpp2: use .mac_select_pcs() interface

[Russell King (Oracle)]

Use the mac_select_pcs() method to choose between the GMAC and XLG
PCS implementations.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2.h    |  3 +-
 .../net/ethernet/marvell/mvpp2/mvpp2_main.c   | 75 ++++++++++---------
 2 files changed, 42 insertions(+), 36 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2.h b/drivers/net/ethernet/marvell/mvpp2/mvpp2.h
index cf8acabb90ac..ad73a488fc5f 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2.h
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2.h
@@ -1239,7 +1239,8 @@ struct mvpp2_port {
 	phy_interface_t phy_interface;
 	struct phylink *phylink;
 	struct phylink_config phylink_config;
-	struct phylink_pcs phylink_pcs;
+	struct phylink_pcs pcs_gmac;
+	struct phylink_pcs pcs_xlg;
 	struct phy *comphy;
 
 	struct mvpp2_bm_pool *pool_long;
diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
index 8e5820d12362..f5e10fe7812b 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
@@ -6118,15 +6118,20 @@ static struct mvpp2_port *mvpp2_phylink_to_port(struct phylink_config *config)
 	return container_of(config, struct mvpp2_port, phylink_config);
 }
 
-static struct mvpp2_port *mvpp2_pcs_to_port(struct phylink_pcs *pcs)
+static struct mvpp2_port *mvpp2_pcs_xlg_to_port(struct phylink_pcs *pcs)
 {
-	return container_of(pcs, struct mvpp2_port, phylink_pcs);
+	return container_of(pcs, struct mvpp2_port, pcs_xlg);
+}
+
+static struct mvpp2_port *mvpp2_pcs_gmac_to_port(struct phylink_pcs *pcs)
+{
+	return container_of(pcs, struct mvpp2_port, pcs_gmac);
 }
 
 static void mvpp2_xlg_pcs_get_state(struct phylink_pcs *pcs,
 				    struct phylink_link_state *state)
 {
-	struct mvpp2_port *port = mvpp2_pcs_to_port(pcs);
+	struct mvpp2_port *port = mvpp2_pcs_xlg_to_port(pcs);
 	u32 val;
 
 	if (port->phy_interface == PHY_INTERFACE_MODE_5GBASER)
@@ -6164,7 +6169,7 @@ static const struct phylink_pcs_ops mvpp2_phylink_xlg_pcs_ops = {
 static void mvpp2_gmac_pcs_get_state(struct phylink_pcs *pcs,
 				     struct phylink_link_state *state)
 {
-	struct mvpp2_port *port = mvpp2_pcs_to_port(pcs);
+	struct mvpp2_port *port = mvpp2_pcs_gmac_to_port(pcs);
 	u32 val;
 
 	val = readl(port->base + MVPP2_GMAC_STATUS0);
@@ -6201,7 +6206,7 @@ static int mvpp2_gmac_pcs_config(struct phylink_pcs *pcs, unsigned int mode,
 				 const unsigned long *advertising,
 				 bool permit_pause_to_mac)
 {
-	struct mvpp2_port *port = mvpp2_pcs_to_port(pcs);
+	struct mvpp2_port *port = mvpp2_pcs_gmac_to_port(pcs);
 	u32 mask, val, an, old_an, changed;
 
 	mask = MVPP2_GMAC_IN_BAND_AUTONEG_BYPASS |
@@ -6255,7 +6260,7 @@ static int mvpp2_gmac_pcs_config(struct phylink_pcs *pcs, unsigned int mode,
 
 static void mvpp2_gmac_pcs_an_restart(struct phylink_pcs *pcs)
 {
-	struct mvpp2_port *port = mvpp2_pcs_to_port(pcs);
+	struct mvpp2_port *port = mvpp2_pcs_gmac_to_port(pcs);
 	u32 val = readl(port->base + MVPP2_GMAC_AUTONEG_CONFIG);
 
 	writel(val | MVPP2_GMAC_IN_BAND_RESTART_AN,
@@ -6368,8 +6373,23 @@ static void mvpp2_gmac_config(struct mvpp2_port *port, unsigned int mode,
 		writel(ctrl4, port->base + MVPP22_GMAC_CTRL_4_REG);
 }
 
-static int mvpp2__mac_prepare(struct phylink_config *config, unsigned int mode,
-			      phy_interface_t interface)
+static struct phylink_pcs *mvpp2_select_pcs(struct phylink_config *config,
+					    phy_interface_t interface)
+{
+	struct mvpp2_port *port = mvpp2_phylink_to_port(config);
+
+	/* Select the appropriate PCS operations depending on the
+	 * configured interface mode. We will only switch to a mode
+	 * that the validate() checks have already passed.
+	 */
+	if (mvpp2_is_xlg(interface))
+		return &port->pcs_xlg;
+	else
+		return &port->pcs_gmac;
+}
+
+static int mvpp2_mac_prepare(struct phylink_config *config, unsigned int mode,
+			     phy_interface_t interface)
 {
 	struct mvpp2_port *port = mvpp2_phylink_to_port(config);
 
@@ -6418,31 +6438,9 @@ static int mvpp2__mac_prepare(struct phylink_config *config, unsigned int mode,
 		}
 	}
 
-	/* Select the appropriate PCS operations depending on the
-	 * configured interface mode. We will only switch to a mode
-	 * that the validate() checks have already passed.
-	 */
-	if (mvpp2_is_xlg(interface))
-		port->phylink_pcs.ops = &mvpp2_phylink_xlg_pcs_ops;
-	else
-		port->phylink_pcs.ops = &mvpp2_phylink_gmac_pcs_ops;
-
 	return 0;
 }
 
-static int mvpp2_mac_prepare(struct phylink_config *config, unsigned int mode,
-			     phy_interface_t interface)
-{
-	struct mvpp2_port *port = mvpp2_phylink_to_port(config);
-	int ret;
-
-	ret = mvpp2__mac_prepare(config, mode, interface);
-	if (ret == 0)
-		phylink_set_pcs(port->phylink, &port->phylink_pcs);
-
-	return ret;
-}
-
 static void mvpp2_mac_config(struct phylink_config *config, unsigned int mode,
 			     const struct phylink_link_state *state)
 {
@@ -6614,6 +6612,7 @@ static void mvpp2_mac_link_down(struct phylink_config *config,
 
 static const struct phylink_mac_ops mvpp2_phylink_ops = {
 	.validate = mvpp2_phylink_validate,
+	.mac_select_pcs = mvpp2_select_pcs,
 	.mac_prepare = mvpp2_mac_prepare,
 	.mac_config = mvpp2_mac_config,
 	.mac_finish = mvpp2_mac_finish,
@@ -6631,12 +6630,15 @@ static void mvpp2_acpi_start(struct mvpp2_port *port)
 	struct phylink_link_state state = {
 		.interface = port->phy_interface,
 	};
-	mvpp2__mac_prepare(&port->phylink_config, MLO_AN_INBAND,
-			   port->phy_interface);
+	struct phylink_pcs *pcs;
+
+	pcs = mvpp2_select_pcs(&port->phylink_config, port->phy_interface);
+
+	mvpp2_mac_prepare(&port->phylink_config, MLO_AN_INBAND,
+			  port->phy_interface);
 	mvpp2_mac_config(&port->phylink_config, MLO_AN_INBAND, &state);
-	port->phylink_pcs.ops->pcs_config(&port->phylink_pcs, MLO_AN_INBAND,
-					  port->phy_interface,
-					  state.advertising, false);
+	pcs->ops->pcs_config(pcs, MLO_AN_INBAND, port->phy_interface,
+			     state.advertising, false);
 	mvpp2_mac_finish(&port->phylink_config, MLO_AN_INBAND,
 			 port->phy_interface);
 	mvpp2_mac_link_up(&port->phylink_config, NULL,
@@ -6944,6 +6946,9 @@ static int mvpp2_port_probe(struct platform_device *pdev,
 				  port->phylink_config.supported_interfaces);
 		}
 
+		port->pcs_gmac.ops = &mvpp2_phylink_gmac_pcs_ops;
+		port->pcs_xlg.ops = &mvpp2_phylink_xlg_pcs_ops;
+
 		phylink = phylink_create(&port->phylink_config, port_fwnode,
 					 phy_mode, &mvpp2_phylink_ops);
 		if (IS_ERR(phylink)) {
-- 
2.30.2

[PATCH net-next 4/7] net: mvpp2: convert to pcs_validate() and phylink_generic_validate()

[Russell King (Oracle)]

Convert mvpp2 to validate the autoneg state for 1000base-X in the
pcs_validate() operation, rather than the MAC validate() operation.
This allows us to switch the MAC validate() to use
phylink_generic_validate().

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 .../net/ethernet/marvell/mvpp2/mvpp2_main.c   | 37 +++++++++----------
 1 file changed, 17 insertions(+), 20 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
index f5e10fe7812b..c5e49bbf462f 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
@@ -6166,6 +6166,21 @@ static const struct phylink_pcs_ops mvpp2_phylink_xlg_pcs_ops = {
 	.pcs_config = mvpp2_xlg_pcs_config,
 };
 
+static int mvpp2_gmac_pcs_validate(struct phylink_pcs *pcs,
+				   unsigned long *supported,
+				   const struct phylink_link_state *state)
+{
+	/* When in 802.3z mode, we must have AN enabled:
+	 * Bit 2 Field InBandAnEn In-band Auto-Negotiation enable. ...
+	 * When <PortType> = 1 (1000BASE-X) this field must be set to 1.
+	 */
+	if (phy_interface_mode_is_8023z(state->interface) &&
+	    !phylink_test(state->advertising, Autoneg))
+		return -EINVAL;
+
+	return 0;
+}
+
 static void mvpp2_gmac_pcs_get_state(struct phylink_pcs *pcs,
 				     struct phylink_link_state *state)
 {
@@ -6270,30 +6285,12 @@ static void mvpp2_gmac_pcs_an_restart(struct phylink_pcs *pcs)
 }
 
 static const struct phylink_pcs_ops mvpp2_phylink_gmac_pcs_ops = {
+	.pcs_validate = mvpp2_gmac_pcs_validate,
 	.pcs_get_state = mvpp2_gmac_pcs_get_state,
 	.pcs_config = mvpp2_gmac_pcs_config,
 	.pcs_an_restart = mvpp2_gmac_pcs_an_restart,
 };
 
-static void mvpp2_phylink_validate(struct phylink_config *config,
-				   unsigned long *supported,
-				   struct phylink_link_state *state)
-{
-	/* When in 802.3z mode, we must have AN enabled:
-	 * Bit 2 Field InBandAnEn In-band Auto-Negotiation enable. ...
-	 * When <PortType> = 1 (1000BASE-X) this field must be set to 1.
-	 */
-	if (phy_interface_mode_is_8023z(state->interface) &&
-	    !phylink_test(state->advertising, Autoneg))
-		goto empty_set;
-
-	phylink_generic_validate(config, supported, state);
-	return;
-
-empty_set:
-	linkmode_zero(supported);
-}
-
 static void mvpp2_xlg_config(struct mvpp2_port *port, unsigned int mode,
 			     const struct phylink_link_state *state)
 {
@@ -6611,7 +6608,7 @@ static void mvpp2_mac_link_down(struct phylink_config *config,
 }
 
 static const struct phylink_mac_ops mvpp2_phylink_ops = {
-	.validate = mvpp2_phylink_validate,
+	.validate = phylink_generic_validate,
 	.mac_select_pcs = mvpp2_select_pcs,
 	.mac_prepare = mvpp2_mac_prepare,
 	.mac_config = mvpp2_mac_config,
-- 
2.30.2

[PATCH net-next 5/7] net: mvneta: convert to use mac_prepare()/mac_finish()

[Russell King]

Convert mvneta to use the mac_prepare() and mac_finish() methods in
preparation to converting mvneta to split-PCS support.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
---
 drivers/net/ethernet/marvell/mvneta.c | 103 +++++++++++++++++---------
 1 file changed, 68 insertions(+), 35 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index e3c5d64ba340..e59952c65a3c 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -3905,6 +3905,40 @@ static void mvneta_mac_an_restart(struct phylink_config *config)
 		    gmac_an & ~MVNETA_GMAC_INBAND_RESTART_AN);
 }
 
+static int mvneta_mac_prepare(struct phylink_config *config, unsigned int mode,
+			      phy_interface_t interface)
+{
+	struct net_device *ndev = to_net_dev(config->dev);
+	struct mvneta_port *pp = netdev_priv(ndev);
+	u32 val;
+
+	if (pp->phy_interface != interface ||
+	    phylink_autoneg_inband(mode)) {
+		/* Force the link down when changing the interface or if in
+		 * in-band mode. According to Armada 370 documentation, we
+		 * can only change the port mode and in-band enable when the
+		 * link is down.
+		 */
+		val = mvreg_read(pp, MVNETA_GMAC_AUTONEG_CONFIG);
+		val &= ~MVNETA_GMAC_FORCE_LINK_PASS;
+		val |= MVNETA_GMAC_FORCE_LINK_DOWN;
+		mvreg_write(pp, MVNETA_GMAC_AUTONEG_CONFIG, val);
+	}
+
+	if (pp->phy_interface != interface)
+		WARN_ON(phy_power_off(pp->comphy));
+
+	/* Enable the 1ms clock */
+	if (phylink_autoneg_inband(mode)) {
+		unsigned long rate = clk_get_rate(pp->clk);
+
+		mvreg_write(pp, MVNETA_GMAC_CLOCK_DIVIDER,
+			    MVNETA_GMAC_1MS_CLOCK_ENABLE | (rate / 1000));
+	}
+
+	return 0;
+}
+
 static void mvneta_mac_config(struct phylink_config *config, unsigned int mode,
 			      const struct phylink_link_state *state)
 {
@@ -3913,14 +3947,12 @@ static void mvneta_mac_config(struct phylink_config *config, unsigned int mode,
 	u32 new_ctrl0, gmac_ctrl0 = mvreg_read(pp, MVNETA_GMAC_CTRL_0);
 	u32 new_ctrl2, gmac_ctrl2 = mvreg_read(pp, MVNETA_GMAC_CTRL_2);
 	u32 new_ctrl4, gmac_ctrl4 = mvreg_read(pp, MVNETA_GMAC_CTRL_4);
-	u32 new_clk, gmac_clk = mvreg_read(pp, MVNETA_GMAC_CLOCK_DIVIDER);
 	u32 new_an, gmac_an = mvreg_read(pp, MVNETA_GMAC_AUTONEG_CONFIG);
 
 	new_ctrl0 = gmac_ctrl0 & ~MVNETA_GMAC0_PORT_1000BASE_X;
 	new_ctrl2 = gmac_ctrl2 & ~(MVNETA_GMAC2_INBAND_AN_ENABLE |
 				   MVNETA_GMAC2_PORT_RESET);
 	new_ctrl4 = gmac_ctrl4 & ~(MVNETA_GMAC4_SHORT_PREAMBLE_ENABLE);
-	new_clk = gmac_clk & ~MVNETA_GMAC_1MS_CLOCK_ENABLE;
 	new_an = gmac_an & ~(MVNETA_GMAC_INBAND_AN_ENABLE |
 			     MVNETA_GMAC_INBAND_RESTART_AN |
 			     MVNETA_GMAC_AN_SPEED_EN |
@@ -3948,10 +3980,7 @@ static void mvneta_mac_config(struct phylink_config *config, unsigned int mode,
 	} else if (state->interface == PHY_INTERFACE_MODE_SGMII) {
 		/* SGMII mode receives the state from the PHY */
 		new_ctrl2 |= MVNETA_GMAC2_INBAND_AN_ENABLE;
-		new_clk = MVNETA_GMAC_1MS_CLOCK_ENABLE;
-		new_an = (new_an & ~(MVNETA_GMAC_FORCE_LINK_DOWN |
-				     MVNETA_GMAC_FORCE_LINK_PASS |
-				     MVNETA_GMAC_CONFIG_MII_SPEED |
+		new_an = (new_an & ~(MVNETA_GMAC_CONFIG_MII_SPEED |
 				     MVNETA_GMAC_CONFIG_GMII_SPEED |
 				     MVNETA_GMAC_CONFIG_FULL_DUPLEX)) |
 			 MVNETA_GMAC_INBAND_AN_ENABLE |
@@ -3960,10 +3989,7 @@ static void mvneta_mac_config(struct phylink_config *config, unsigned int mode,
 	} else {
 		/* 802.3z negotiation - only 1000base-X */
 		new_ctrl0 |= MVNETA_GMAC0_PORT_1000BASE_X;
-		new_clk = MVNETA_GMAC_1MS_CLOCK_ENABLE;
-		new_an = (new_an & ~(MVNETA_GMAC_FORCE_LINK_DOWN |
-				     MVNETA_GMAC_FORCE_LINK_PASS |
-				     MVNETA_GMAC_CONFIG_MII_SPEED)) |
+		new_an = (new_an & ~MVNETA_GMAC_CONFIG_MII_SPEED) |
 			 MVNETA_GMAC_INBAND_AN_ENABLE |
 			 MVNETA_GMAC_CONFIG_GMII_SPEED |
 			 /* The MAC only supports FD mode */
@@ -3973,43 +3999,18 @@ static void mvneta_mac_config(struct phylink_config *config, unsigned int mode,
 			new_an |= MVNETA_GMAC_AN_FLOW_CTRL_EN;
 	}
 
-	/* Set the 1ms clock divisor */
-	if (new_clk == MVNETA_GMAC_1MS_CLOCK_ENABLE)
-		new_clk |= clk_get_rate(pp->clk) / 1000;
-
-	/* Armada 370 documentation says we can only change the port mode
-	 * and in-band enable when the link is down, so force it down
-	 * while making these changes. We also do this for GMAC_CTRL2
-	 */
-	if ((new_ctrl0 ^ gmac_ctrl0) & MVNETA_GMAC0_PORT_1000BASE_X ||
-	    (new_ctrl2 ^ gmac_ctrl2) & MVNETA_GMAC2_INBAND_AN_ENABLE ||
-	    (new_an  ^ gmac_an) & MVNETA_GMAC_INBAND_AN_ENABLE) {
-		mvreg_write(pp, MVNETA_GMAC_AUTONEG_CONFIG,
-			    (gmac_an & ~MVNETA_GMAC_FORCE_LINK_PASS) |
-			    MVNETA_GMAC_FORCE_LINK_DOWN);
-	}
-
-
 	/* When at 2.5G, the link partner can send frames with shortened
 	 * preambles.
 	 */
 	if (state->interface == PHY_INTERFACE_MODE_2500BASEX)
 		new_ctrl4 |= MVNETA_GMAC4_SHORT_PREAMBLE_ENABLE;
 
-	if (pp->phy_interface != state->interface) {
-		if (pp->comphy)
-			WARN_ON(phy_power_off(pp->comphy));
-		WARN_ON(mvneta_config_interface(pp, state->interface));
-	}
-
 	if (new_ctrl0 != gmac_ctrl0)
 		mvreg_write(pp, MVNETA_GMAC_CTRL_0, new_ctrl0);
 	if (new_ctrl2 != gmac_ctrl2)
 		mvreg_write(pp, MVNETA_GMAC_CTRL_2, new_ctrl2);
 	if (new_ctrl4 != gmac_ctrl4)
 		mvreg_write(pp, MVNETA_GMAC_CTRL_4, new_ctrl4);
-	if (new_clk != gmac_clk)
-		mvreg_write(pp, MVNETA_GMAC_CLOCK_DIVIDER, new_clk);
 	if (new_an != gmac_an)
 		mvreg_write(pp, MVNETA_GMAC_AUTONEG_CONFIG, new_an);
 
@@ -4020,6 +4021,36 @@ static void mvneta_mac_config(struct phylink_config *config, unsigned int mode,
 	}
 }
 
+static int mvneta_mac_finish(struct phylink_config *config, unsigned int mode,
+			     phy_interface_t interface)
+{
+	struct net_device *ndev = to_net_dev(config->dev);
+	struct mvneta_port *pp = netdev_priv(ndev);
+	u32 val, clk;
+
+	/* Disable 1ms clock if not in in-band mode */
+	if (!phylink_autoneg_inband(mode)) {
+		clk = mvreg_read(pp, MVNETA_GMAC_CLOCK_DIVIDER);
+		clk &= ~MVNETA_GMAC_1MS_CLOCK_ENABLE;
+		mvreg_write(pp, MVNETA_GMAC_CLOCK_DIVIDER, clk);
+	}
+
+	if (pp->phy_interface != interface)
+		/* Enable the Serdes PHY */
+		WARN_ON(mvneta_config_interface(pp, interface));
+
+	/* Allow the link to come up if in in-band mode, otherwise the
+	 * link is forced via mac_link_down()/mac_link_up()
+	 */
+	if (phylink_autoneg_inband(mode)) {
+		val = mvreg_read(pp, MVNETA_GMAC_AUTONEG_CONFIG);
+		val &= ~MVNETA_GMAC_FORCE_LINK_DOWN;
+		mvreg_write(pp, MVNETA_GMAC_AUTONEG_CONFIG, val);
+	}
+
+	return 0;
+}
+
 static void mvneta_set_eee(struct mvneta_port *pp, bool enable)
 {
 	u32 lpi_ctl1;
@@ -4109,7 +4140,9 @@ static const struct phylink_mac_ops mvneta_phylink_ops = {
 	.validate = mvneta_validate,
 	.mac_pcs_get_state = mvneta_mac_pcs_get_state,
 	.mac_an_restart = mvneta_mac_an_restart,
+	.mac_prepare = mvneta_mac_prepare,
 	.mac_config = mvneta_mac_config,
+	.mac_finish = mvneta_mac_finish,
 	.mac_link_down = mvneta_mac_link_down,
 	.mac_link_up = mvneta_mac_link_up,
 };
-- 
2.30.2

[PATCH net-next 6/7] net: mvneta: convert to phylink pcs operations

[Russell King]

An initial stab at converting mvneta to PCS operations.  There's a few
FIXMEs to be solved.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
---
 drivers/net/ethernet/marvell/mvneta.c | 143 ++++++++++++++++----------
 1 file changed, 91 insertions(+), 52 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index e59952c65a3c..f40eb282c522 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -526,6 +526,7 @@ struct mvneta_port {
 	unsigned int tx_csum_limit;
 	struct phylink *phylink;
 	struct phylink_config phylink_config;
+	struct phylink_pcs phylink_pcs;
 	struct phy *comphy;
 
 	struct mvneta_bm *bm_priv;
@@ -3846,29 +3847,15 @@ static int mvneta_set_mac_addr(struct net_device *dev, void *addr)
 	return 0;
 }
 
-static void mvneta_validate(struct phylink_config *config,
-			    unsigned long *supported,
-			    struct phylink_link_state *state)
+static struct mvneta_port *mvneta_pcs_to_port(struct phylink_pcs *pcs)
 {
-	/* We only support QSGMII, SGMII, 802.3z and RGMII modes.
-	 * When in 802.3z mode, we must have AN enabled:
-	 * "Bit 2 Field InBandAnEn In-band Auto-Negotiation enable. ...
-	 * When <PortType> = 1 (1000BASE-X) this field must be set to 1."
-	 */
-	if (phy_interface_mode_is_8023z(state->interface) &&
-	    !phylink_test(state->advertising, Autoneg)) {
-		linkmode_zero(supported);
-		return;
-	}
-
-	phylink_generic_validate(config, supported, state);
+	return container_of(pcs, struct mvneta_port, phylink_pcs);
 }
 
-static void mvneta_mac_pcs_get_state(struct phylink_config *config,
-				     struct phylink_link_state *state)
+static void mvneta_pcs_get_state(struct phylink_pcs *pcs,
+				 struct phylink_link_state *state)
 {
-	struct net_device *ndev = to_net_dev(config->dev);
-	struct mvneta_port *pp = netdev_priv(ndev);
+	struct mvneta_port *pp = mvneta_pcs_to_port(pcs);
 	u32 gmac_stat;
 
 	gmac_stat = mvreg_read(pp, MVNETA_GMAC_STATUS);
@@ -3886,17 +3873,71 @@ static void mvneta_mac_pcs_get_state(struct phylink_config *config,
 	state->link = !!(gmac_stat & MVNETA_GMAC_LINK_UP);
 	state->duplex = !!(gmac_stat & MVNETA_GMAC_FULL_DUPLEX);
 
-	state->pause = 0;
 	if (gmac_stat & MVNETA_GMAC_RX_FLOW_CTRL_ENABLE)
 		state->pause |= MLO_PAUSE_RX;
 	if (gmac_stat & MVNETA_GMAC_TX_FLOW_CTRL_ENABLE)
 		state->pause |= MLO_PAUSE_TX;
 }
 
-static void mvneta_mac_an_restart(struct phylink_config *config)
+static int mvneta_pcs_config(struct phylink_pcs *pcs,
+			     unsigned int mode, phy_interface_t interface,
+			     const unsigned long *advertising,
+			     bool permit_pause_to_mac)
 {
-	struct net_device *ndev = to_net_dev(config->dev);
-	struct mvneta_port *pp = netdev_priv(ndev);
+	struct mvneta_port *pp = mvneta_pcs_to_port(pcs);
+	u32 mask, val, an, old_an, changed;
+
+	mask = MVNETA_GMAC_INBAND_AN_ENABLE |
+	       MVNETA_GMAC_INBAND_RESTART_AN |
+	       MVNETA_GMAC_AN_SPEED_EN |
+	       MVNETA_GMAC_AN_FLOW_CTRL_EN |
+	       MVNETA_GMAC_AN_DUPLEX_EN;
+
+	if (phylink_autoneg_inband(mode)) {
+		mask |= MVNETA_GMAC_CONFIG_MII_SPEED |
+			MVNETA_GMAC_CONFIG_GMII_SPEED |
+			MVNETA_GMAC_CONFIG_FULL_DUPLEX;
+		val = MVNETA_GMAC_INBAND_AN_ENABLE;
+
+		if (interface == PHY_INTERFACE_MODE_SGMII) {
+			/* SGMII mode receives the speed and duplex from PHY */
+			val |= MVNETA_GMAC_AN_SPEED_EN |
+			       MVNETA_GMAC_AN_DUPLEX_EN;
+		} else {
+			/* 802.3z mode has fixed speed and duplex */
+			val |= MVNETA_GMAC_CONFIG_GMII_SPEED |
+			       MVNETA_GMAC_CONFIG_FULL_DUPLEX;
+
+			/* The FLOW_CTRL_EN bit selects either the hardware
+			 * automatically or the CONFIG_FLOW_CTRL manually
+			 * controls the GMAC pause mode.
+			 */
+			if (permit_pause_to_mac)
+				val |= MVNETA_GMAC_AN_FLOW_CTRL_EN;
+
+			/* Update the advertisement bits */
+			mask |= MVNETA_GMAC_ADVERT_SYM_FLOW_CTRL;
+			if (phylink_test(advertising, Pause))
+				val |= MVNETA_GMAC_ADVERT_SYM_FLOW_CTRL;
+		}
+	} else {
+		/* Phy or fixed speed - disable in-band AN modes */
+		val = 0;
+	}
+
+	old_an = an = mvreg_read(pp, MVNETA_GMAC_AUTONEG_CONFIG);
+	an = (an & ~mask) | val;
+	changed = old_an ^ an;
+	if (changed)
+		mvreg_write(pp, MVNETA_GMAC_AUTONEG_CONFIG, an);
+
+	/* We are only interested in the advertisement bits changing */
+	return !!(changed & MVNETA_GMAC_ADVERT_SYM_FLOW_CTRL);
+}
+
+static void mvneta_pcs_an_restart(struct phylink_pcs *pcs)
+{
+	struct mvneta_port *pp = mvneta_pcs_to_port(pcs);
 	u32 gmac_an = mvreg_read(pp, MVNETA_GMAC_AUTONEG_CONFIG);
 
 	mvreg_write(pp, MVNETA_GMAC_AUTONEG_CONFIG,
@@ -3905,6 +3946,30 @@ static void mvneta_mac_an_restart(struct phylink_config *config)
 		    gmac_an & ~MVNETA_GMAC_INBAND_RESTART_AN);
 }
 
+static const struct phylink_pcs_ops mvneta_phylink_pcs_ops = {
+	.pcs_get_state = mvneta_pcs_get_state,
+	.pcs_config = mvneta_pcs_config,
+	.pcs_an_restart = mvneta_pcs_an_restart,
+};
+
+static void mvneta_validate(struct phylink_config *config,
+			    unsigned long *supported,
+			    struct phylink_link_state *state)
+{
+	/* We only support QSGMII, SGMII, 802.3z and RGMII modes.
+	 * When in 802.3z mode, we must have AN enabled:
+	 * "Bit 2 Field InBandAnEn In-band Auto-Negotiation enable. ...
+	 * When <PortType> = 1 (1000BASE-X) this field must be set to 1."
+	 */
+	if (phy_interface_mode_is_8023z(state->interface) &&
+	    !phylink_test(state->advertising, Autoneg)) {
+		linkmode_zero(supported);
+		return;
+	}
+
+	phylink_generic_validate(config, supported, state);
+}
+
 static int mvneta_mac_prepare(struct phylink_config *config, unsigned int mode,
 			      phy_interface_t interface)
 {
@@ -3947,18 +4012,11 @@ static void mvneta_mac_config(struct phylink_config *config, unsigned int mode,
 	u32 new_ctrl0, gmac_ctrl0 = mvreg_read(pp, MVNETA_GMAC_CTRL_0);
 	u32 new_ctrl2, gmac_ctrl2 = mvreg_read(pp, MVNETA_GMAC_CTRL_2);
 	u32 new_ctrl4, gmac_ctrl4 = mvreg_read(pp, MVNETA_GMAC_CTRL_4);
-	u32 new_an, gmac_an = mvreg_read(pp, MVNETA_GMAC_AUTONEG_CONFIG);
 
 	new_ctrl0 = gmac_ctrl0 & ~MVNETA_GMAC0_PORT_1000BASE_X;
 	new_ctrl2 = gmac_ctrl2 & ~(MVNETA_GMAC2_INBAND_AN_ENABLE |
 				   MVNETA_GMAC2_PORT_RESET);
 	new_ctrl4 = gmac_ctrl4 & ~(MVNETA_GMAC4_SHORT_PREAMBLE_ENABLE);
-	new_an = gmac_an & ~(MVNETA_GMAC_INBAND_AN_ENABLE |
-			     MVNETA_GMAC_INBAND_RESTART_AN |
-			     MVNETA_GMAC_AN_SPEED_EN |
-			     MVNETA_GMAC_ADVERT_SYM_FLOW_CTRL |
-			     MVNETA_GMAC_AN_FLOW_CTRL_EN |
-			     MVNETA_GMAC_AN_DUPLEX_EN);
 
 	/* Even though it might look weird, when we're configured in
 	 * SGMII or QSGMII mode, the RGMII bit needs to be set.
@@ -3970,9 +4028,6 @@ static void mvneta_mac_config(struct phylink_config *config, unsigned int mode,
 	    phy_interface_mode_is_8023z(state->interface))
 		new_ctrl2 |= MVNETA_GMAC2_PCS_ENABLE;
 
-	if (phylink_test(state->advertising, Pause))
-		new_an |= MVNETA_GMAC_ADVERT_SYM_FLOW_CTRL;
-
 	if (!phylink_autoneg_inband(mode)) {
 		/* Phy or fixed speed - nothing to do, leave the
 		 * configured speed, duplex and flow control as-is.
@@ -3980,23 +4035,9 @@ static void mvneta_mac_config(struct phylink_config *config, unsigned int mode,
 	} else if (state->interface == PHY_INTERFACE_MODE_SGMII) {
 		/* SGMII mode receives the state from the PHY */
 		new_ctrl2 |= MVNETA_GMAC2_INBAND_AN_ENABLE;
-		new_an = (new_an & ~(MVNETA_GMAC_CONFIG_MII_SPEED |
-				     MVNETA_GMAC_CONFIG_GMII_SPEED |
-				     MVNETA_GMAC_CONFIG_FULL_DUPLEX)) |
-			 MVNETA_GMAC_INBAND_AN_ENABLE |
-			 MVNETA_GMAC_AN_SPEED_EN |
-			 MVNETA_GMAC_AN_DUPLEX_EN;
 	} else {
 		/* 802.3z negotiation - only 1000base-X */
 		new_ctrl0 |= MVNETA_GMAC0_PORT_1000BASE_X;
-		new_an = (new_an & ~MVNETA_GMAC_CONFIG_MII_SPEED) |
-			 MVNETA_GMAC_INBAND_AN_ENABLE |
-			 MVNETA_GMAC_CONFIG_GMII_SPEED |
-			 /* The MAC only supports FD mode */
-			 MVNETA_GMAC_CONFIG_FULL_DUPLEX;
-
-		if (state->pause & MLO_PAUSE_AN && state->an_enabled)
-			new_an |= MVNETA_GMAC_AN_FLOW_CTRL_EN;
 	}
 
 	/* When at 2.5G, the link partner can send frames with shortened
@@ -4011,8 +4052,6 @@ static void mvneta_mac_config(struct phylink_config *config, unsigned int mode,
 		mvreg_write(pp, MVNETA_GMAC_CTRL_2, new_ctrl2);
 	if (new_ctrl4 != gmac_ctrl4)
 		mvreg_write(pp, MVNETA_GMAC_CTRL_4, new_ctrl4);
-	if (new_an != gmac_an)
-		mvreg_write(pp, MVNETA_GMAC_AUTONEG_CONFIG, new_an);
 
 	if (gmac_ctrl2 & MVNETA_GMAC2_PORT_RESET) {
 		while ((mvreg_read(pp, MVNETA_GMAC_CTRL_2) &
@@ -4138,8 +4177,6 @@ static void mvneta_mac_link_up(struct phylink_config *config,
 
 static const struct phylink_mac_ops mvneta_phylink_ops = {
 	.validate = mvneta_validate,
-	.mac_pcs_get_state = mvneta_mac_pcs_get_state,
-	.mac_an_restart = mvneta_mac_an_restart,
 	.mac_prepare = mvneta_mac_prepare,
 	.mac_config = mvneta_mac_config,
 	.mac_finish = mvneta_mac_finish,
@@ -5308,7 +5345,6 @@ static int mvneta_probe(struct platform_device *pdev)
 
 	pp->phylink_config.dev = &dev->dev;
 	pp->phylink_config.type = PHYLINK_NETDEV;
-	pp->phylink_config.legacy_pre_march2020 = true;
 	pp->phylink_config.mac_capabilities = MAC_SYM_PAUSE | MAC_10 |
 		MAC_100 | MAC_1000FD | MAC_2500FD;
 
@@ -5383,6 +5419,9 @@ static int mvneta_probe(struct platform_device *pdev)
 		goto err_clk;
 	}
 
+	pp->phylink_pcs.ops = &mvneta_phylink_pcs_ops;
+	phylink_set_pcs(phylink, &pp->phylink_pcs);
+
 	/* Alloc per-cpu port structure */
 	pp->ports = alloc_percpu(struct mvneta_pcpu_port);
 	if (!pp->ports) {
-- 
2.30.2

[PATCH net-next 7/7] net: mvneta: convert to pcs_validate() and phylink_generic_validate()

[Russell King (Oracle)]

Convert mvneta to validate the autoneg state for 1000base-X in the
pcs_validate() operation, rather than the MAC validate() operation.
This allows us to switch the MAC validate() to use
phylink_generic_validate().

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 drivers/net/ethernet/marvell/mvneta.c | 37 +++++++++++++--------------
 1 file changed, 18 insertions(+), 19 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index f40eb282c522..e4c328f61188 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -3852,6 +3852,22 @@ static struct mvneta_port *mvneta_pcs_to_port(struct phylink_pcs *pcs)
 	return container_of(pcs, struct mvneta_port, phylink_pcs);
 }
 
+static int mvneta_pcs_validate(struct phylink_pcs *pcs,
+			       unsigned long *supported,
+			       const struct phylink_link_state *state)
+{
+	/* We only support QSGMII, SGMII, 802.3z and RGMII modes.
+	 * When in 802.3z mode, we must have AN enabled:
+	 * "Bit 2 Field InBandAnEn In-band Auto-Negotiation enable. ...
+	 * When <PortType> = 1 (1000BASE-X) this field must be set to 1."
+	 */
+	if (phy_interface_mode_is_8023z(state->interface) &&
+	    !phylink_test(state->advertising, Autoneg))
+		return -EINVAL;
+
+	return 0;
+}
+
 static void mvneta_pcs_get_state(struct phylink_pcs *pcs,
 				 struct phylink_link_state *state)
 {
@@ -3947,29 +3963,12 @@ static void mvneta_pcs_an_restart(struct phylink_pcs *pcs)
 }
 
 static const struct phylink_pcs_ops mvneta_phylink_pcs_ops = {
+	.pcs_validate = mvneta_pcs_validate,
 	.pcs_get_state = mvneta_pcs_get_state,
 	.pcs_config = mvneta_pcs_config,
 	.pcs_an_restart = mvneta_pcs_an_restart,
 };
 
-static void mvneta_validate(struct phylink_config *config,
-			    unsigned long *supported,
-			    struct phylink_link_state *state)
-{
-	/* We only support QSGMII, SGMII, 802.3z and RGMII modes.
-	 * When in 802.3z mode, we must have AN enabled:
-	 * "Bit 2 Field InBandAnEn In-band Auto-Negotiation enable. ...
-	 * When <PortType> = 1 (1000BASE-X) this field must be set to 1."
-	 */
-	if (phy_interface_mode_is_8023z(state->interface) &&
-	    !phylink_test(state->advertising, Autoneg)) {
-		linkmode_zero(supported);
-		return;
-	}
-
-	phylink_generic_validate(config, supported, state);
-}
-
 static int mvneta_mac_prepare(struct phylink_config *config, unsigned int mode,
 			      phy_interface_t interface)
 {
@@ -4176,7 +4175,7 @@ static void mvneta_mac_link_up(struct phylink_config *config,
 }
 
 static const struct phylink_mac_ops mvneta_phylink_ops = {
-	.validate = mvneta_validate,
+	.validate = phylink_generic_validate,
 	.mac_prepare = mvneta_mac_prepare,
 	.mac_config = mvneta_mac_config,
 	.mac_finish = mvneta_mac_finish,
-- 
2.30.2

Re: [PATCH net-next 2/7] net: phylink: add pcs_validate() method

[Sean Anderson]

Hi Russell,

On 12/14/21 9:48 AM, Russell King (Oracle) wrote:
> Add a hook for PCS to validate the link parameters. This avoids MAC
> drivers having to have knowledge of their PCS in their validate()
> method, thereby allowing several MAC drivers to be simplfied.
>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> ---
>   drivers/net/phy/phylink.c | 31 +++++++++++++++++++++++++++++++
>   include/linux/phylink.h   | 20 ++++++++++++++++++++
>   2 files changed, 51 insertions(+)
>
> diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
> index c7035d65e159..420201858564 100644
> --- a/drivers/net/phy/phylink.c
> +++ b/drivers/net/phy/phylink.c
> @@ -424,13 +424,44 @@ static int phylink_validate_mac_and_pcs(struct phylink *pl,
>   					struct phylink_link_state *state)
>   {
>   	struct phylink_pcs *pcs;
> +	int ret;
>
> +	/* Get the PCS for this interface mode */
>   	if (pl->mac_ops->mac_select_pcs) {
>   		pcs = pl->mac_ops->mac_select_pcs(pl->config, state->interface);
>   		if (IS_ERR(pcs))
>   			return PTR_ERR(pcs);
> +	} else {
> +		pcs = pl->pcs;
> +	}
> +
> +	if (pcs) {
> +		/* The PCS, if present, must be setup before phylink_create()
> +		 * has been called. If the ops is not initialised, print an
> +		 * error and backtrace rather than oopsing the kernel.
> +		 */
> +		if (!pcs->ops) {
> +			phylink_err(pl, "interface %s: uninitialised PCS\n",
> +				    phy_modes(state->interface));
> +			dump_stack();
> +			return -EINVAL;
> +		}
> +
> +		/* Validate the link parameters with the PCS */
> +		if (pcs->ops->pcs_validate) {
> +			ret = pcs->ops->pcs_validate(pcs, supported, state);

I wonder if we can add a pcs->supported_interfaces. That would let me
write something like

static int xilinx_pcs_validate(struct phylink_pcs *pcs,
			       unsigned long *supported,
			       struct phylink_link_state *state)
{
	__ETHTOOL_DECLARE_LINK_MODE_MASK(mask) = { 0, };

	phylink_set_port_modes(mask);
	phylink_set(mask, Autoneg);
	phylink_get_linkmodes(mask, state->interface,
			      MAC_10FD | MAC_100FD | MAC_1000FD);

	linkmode_and(supported, supported, mask);
}

And of course, the above could become phylink_pcs_validate_generic with
the addition of a pcs->pcs_capabilities member.

The only wrinkle is that we need to handle PHY_INTERFACE_MODE_NA,
because of the pcs = pl->pcs assignment above. This would require doing
the phylink_validate_any dance again.

Maybe the best way is to stick

	if (state->interface == PHY_INTERFACE_MODE_NA)
		return -EINVAL;

at the top of phylink_pcs_validate_generic (perhaps with a warning).
That would catch any MACs who use a PCS which wants the MAC to have
supported_interfaces.

> +			if (ret < 0 || phylink_is_empty_linkmode(supported))
> +				return -EINVAL;
> +
> +			/* Ensure the advertising mask is a subset of the
> +			 * supported mask.
> +			 */
> +			linkmode_and(state->advertising, state->advertising,
> +				     supported);
> +		}
>   	}
>
> +	/* Then validate the link parameters with the MAC */
>   	pl->mac_ops->validate(pl->config, supported, state);

Shouldn't the PCS stuff happen here? Later in the series, you do things
like

	if (phy_interface_mode_is_8023z(state->interface) &&
	    !phylink_test(state->advertising, Autoneg))
		return -EINVAL;

but there's nothing to stop a mac validate from coming along and saying
"we don't support autonegotiation".

--Sean

Re: [PATCH net-next 2/7] net: phylink: add pcs_validate() method

[Russell King (Oracle)]

On Tue, Dec 14, 2021 at 02:49:13PM -0500, Sean Anderson wrote:
> Hi Russell,
> 
> On 12/14/21 9:48 AM, Russell King (Oracle) wrote:
> > Add a hook for PCS to validate the link parameters. This avoids MAC
> > drivers having to have knowledge of their PCS in their validate()
> > method, thereby allowing several MAC drivers to be simplfied.
> > 
> > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> > ---
> >   drivers/net/phy/phylink.c | 31 +++++++++++++++++++++++++++++++
> >   include/linux/phylink.h   | 20 ++++++++++++++++++++
> >   2 files changed, 51 insertions(+)
> > 
> > diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
> > index c7035d65e159..420201858564 100644
> > --- a/drivers/net/phy/phylink.c
> > +++ b/drivers/net/phy/phylink.c
> > @@ -424,13 +424,44 @@ static int phylink_validate_mac_and_pcs(struct phylink *pl,
> >   					struct phylink_link_state *state)
> >   {
> >   	struct phylink_pcs *pcs;
> > +	int ret;
> > 
> > +	/* Get the PCS for this interface mode */
> >   	if (pl->mac_ops->mac_select_pcs) {
> >   		pcs = pl->mac_ops->mac_select_pcs(pl->config, state->interface);
> >   		if (IS_ERR(pcs))
> >   			return PTR_ERR(pcs);
> > +	} else {
> > +		pcs = pl->pcs;
> > +	}
> > +
> > +	if (pcs) {
> > +		/* The PCS, if present, must be setup before phylink_create()
> > +		 * has been called. If the ops is not initialised, print an
> > +		 * error and backtrace rather than oopsing the kernel.
> > +		 */
> > +		if (!pcs->ops) {
> > +			phylink_err(pl, "interface %s: uninitialised PCS\n",
> > +				    phy_modes(state->interface));
> > +			dump_stack();
> > +			return -EINVAL;
> > +		}
> > +
> > +		/* Validate the link parameters with the PCS */
> > +		if (pcs->ops->pcs_validate) {
> > +			ret = pcs->ops->pcs_validate(pcs, supported, state);
> 
> I wonder if we can add a pcs->supported_interfaces. That would let me
> write something like

I have two arguments against that:

1) Given that .mac_select_pcs should not return a PCS that is not
   appropriate for the provided state->interface, I don't see what
   use having a supported_interfaces member in the PCS would give.
   All that phylink would end up doing is validating that the MAC
   was giving us a sane PCS.

2) In the case of a static PCS (in other words, one attached just
   after phylink_create_pcs()) the PCS is known at creation time,
   so limiting phylink_config.supported_interfaces according to the
   single attached interface seems sane, rather than phylink having
   to repeatedly recalculate the bitwise-and between both
   supported_interface masks.

> static int xilinx_pcs_validate(struct phylink_pcs *pcs,
> 			       unsigned long *supported,
> 			       struct phylink_link_state *state)
> {
> 	__ETHTOOL_DECLARE_LINK_MODE_MASK(mask) = { 0, };
> 
> 	phylink_set_port_modes(mask);
> 	phylink_set(mask, Autoneg);
> 	phylink_get_linkmodes(mask, state->interface,
> 			      MAC_10FD | MAC_100FD | MAC_1000FD);
> 
> 	linkmode_and(supported, supported, mask);
> }

This would be buggy - doesn't the PCS allow pause frames through?

I already have a conversion for axienet in my tree, and it doesn't
need a pcs_validate() implementation. I'll provide it below.

> And of course, the above could become phylink_pcs_validate_generic with
> the addition of a pcs->pcs_capabilities member.
> 
> The only wrinkle is that we need to handle PHY_INTERFACE_MODE_NA,
> because of the pcs = pl->pcs assignment above. This would require doing
> the phylink_validate_any dance again.

Why do you think PHY_INTERFACE_MODE_NA needs handling? If this is not
set in phylink_config.supported_interfaces (which it should never be)
then none of the validation will be called with this.

The special PHY_INTERFACE_MODE_NA meaning "give us everything you have"
is something I want to get rid of, and is something that I am already
explicitly not supporting for pcs_validate(). It doesn't work with the
mac_select_pcs() model, since that can't return all PCS that may be
used.

> 	if (state->interface == PHY_INTERFACE_MODE_NA)
> 		return -EINVAL;
> 
> at the top of phylink_pcs_validate_generic (perhaps with a warning).
> That would catch any MACs who use a PCS which wants the MAC to have
> supported_interfaces.

... which could be too late.

> > +			if (ret < 0 || phylink_is_empty_linkmode(supported))
> > +				return -EINVAL;
> > +
> > +			/* Ensure the advertising mask is a subset of the
> > +			 * supported mask.
> > +			 */
> > +			linkmode_and(state->advertising, state->advertising,
> > +				     supported);
> > +		}
> >   	}
> > 
> > +	/* Then validate the link parameters with the MAC */
> >   	pl->mac_ops->validate(pl->config, supported, state);
> 
> Shouldn't the PCS stuff happen here? Later in the series, you do things
> like
> 
> 	if (phy_interface_mode_is_8023z(state->interface) &&
> 	    !phylink_test(state->advertising, Autoneg))
> 		return -EINVAL;
> 
> but there's nothing to stop a mac validate from coming along and saying
> "we don't support autonegotiation".

How is autonegotiation a property of the MAC when there is a PCS?
In what situation is autonegotiation terminated at the MAC when
there is a PCS present?

The only case I can think of is where the PCS is tightly tied to the
MAC, and in that case you end up with a choice whether or not to model
a PCS in software. This is the case with mvneta and mvpp2 - there is
no separation of the MAC and PCS in the hardware register design. There
is one register that controls pause/duplex advertisement and speeds
irrespective of the PHY interface, whether the interface mode to the
external world is 1000BASE-X, SGMII, QSGMII, RGMII etc. mvpp2 is
slightly different in that it re-uses the GMAC design from mvneta for
speeds <= 2.5G, and an entirely separate XLG implementation for 5G
and 10G. Here, we model these as two separate PCS that we choose
between depending on the interface.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

Re: [PATCH net-next 2/7] net: phylink: add pcs_validate() method

[Russell King (Oracle)]

On Tue, Dec 14, 2021 at 11:27:22PM +0000, Russell King (Oracle) wrote:
> I already have a conversion for axienet in my tree, and it doesn't
> need a pcs_validate() implementation. I'll provide it below.

Forgot to do so... this is obviously untested on real hardware.

8<===
From: "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>
Subject: [PATCH] net: axienet: convert to phylink_pcs

Convert axienet to use the phylink_pcs layer, resulting in it no longer
being a legacy driver.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 drivers/net/ethernet/xilinx/xilinx_axienet.h  |   1 +
 .../net/ethernet/xilinx/xilinx_axienet_main.c | 109 +++++++++---------
 2 files changed, 53 insertions(+), 57 deletions(-)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet.h b/drivers/net/ethernet/xilinx/xilinx_axienet.h
index 5b4d153b1492..81f09bd8f11c 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet.h
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet.h
@@ -434,6 +434,7 @@ struct axienet_local {
 	struct phylink_config phylink_config;
 
 	struct mdio_device *pcs_phy;
+	struct phylink_pcs pcs;
 
 	bool switch_x_sgmii;
 
diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index 25082ff3794b..8d90e887c3e5 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -1503,78 +1503,75 @@ static const struct ethtool_ops axienet_ethtool_ops = {
 	.nway_reset	= axienet_ethtools_nway_reset,
 };
 
-static void axienet_mac_pcs_get_state(struct phylink_config *config,
-				      struct phylink_link_state *state)
+static struct axienet_local *pcs_to_axienet_local(struct phylink_pcs *pcs)
 {
-	struct net_device *ndev = to_net_dev(config->dev);
-	struct axienet_local *lp = netdev_priv(ndev);
+	return container_of(pcs, struct axienet_local, pcs);
+}
 
-	switch (state->interface) {
-	case PHY_INTERFACE_MODE_SGMII:
-	case PHY_INTERFACE_MODE_1000BASEX:
-		phylink_mii_c22_pcs_get_state(lp->pcs_phy, state);
-		break;
-	default:
-		break;
-	}
+static void axienet_pcs_get_state(struct phylink_pcs *pcs,
+				  struct phylink_link_state *state)
+{
+	struct mdio_device *pcs_phy = pcs_to_axienet_local(pcs)->pcs_phy;
+
+	phylink_mii_c22_pcs_get_state(pcs_phy, state);
 }
 
-static void axienet_mac_an_restart(struct phylink_config *config)
+static void axienet_pcs_an_restart(struct phylink_pcs *pcs)
 {
-	struct net_device *ndev = to_net_dev(config->dev);
-	struct axienet_local *lp = netdev_priv(ndev);
+	struct mdio_device *pcs_phy = pcs_to_axienet_local(pcs)->pcs_phy;
 
-	phylink_mii_c22_pcs_an_restart(lp->pcs_phy);
+	phylink_mii_c22_pcs_an_restart(pcs_phy);
 }
 
-static int axienet_mac_prepare(struct phylink_config *config, unsigned int mode,
-			       phy_interface_t iface)
+static int axienet_pcs_config(struct phylink_config *pcs, unsigned int mode,
+			      phy_interface_t interface,
+			      const unsigned long *advertising,
+			      bool permit_pause_to_mac)
 {
-	struct net_device *ndev = to_net_dev(config->dev);
-	struct axienet_local *lp = netdev_priv(ndev);
+	struct net_device *ndev = pcs_to_axienet_local(pcs)->ndev;
+	struct mdio_device *pcs_phy = pcs_to_axienet_local(pcs)->pcs_phy;
 	int ret;
 
-	switch (iface) {
-	case PHY_INTERFACE_MODE_SGMII:
-	case PHY_INTERFACE_MODE_1000BASEX:
-		if (!lp->switch_x_sgmii)
-			return 0;
-
-		ret = mdiobus_write(lp->pcs_phy->bus,
-				    lp->pcs_phy->addr,
-				    XLNX_MII_STD_SELECT_REG,
-				    iface == PHY_INTERFACE_MODE_SGMII ?
-					XLNX_MII_STD_SELECT_SGMII : 0);
-		if (ret < 0)
-			netdev_warn(ndev, "Failed to switch PHY interface: %d\n",
-				    ret);
+	ret = mdiobus_write(pcs_phy->bus, pcs_phy->addr,
+			    XLNX_MII_STD_SELECT_REG,
+			    iface == PHY_INTERFACE_MODE_SGMII ?
+				XLNX_MII_STD_SELECT_SGMII : 0);
+	if (ret < 0) {
+		netdev_warn(ndev, "Failed to switch PHY interface: %d\n",
+			    ret);
 		return ret;
-	default:
-		return 0;
 	}
+
+	ret = phylink_mii_c22_pcs_config(pcs_phy, mode, interface, advertising);
+	if (ret < 0)
+		netdev_warn(ndev, "Failed to configure PCS: %d\n", ret);
+
+	return ret;
 }
 
-static void axienet_mac_config(struct phylink_config *config, unsigned int mode,
-			       const struct phylink_link_state *state)
+static const struct phylink_pcs_ops axienet_pcs_ops = {
+	.pcs_get_state = axienet_pcs_get_state,
+	.pcs_config = axienet_pcs_config,
+	.pcs_an_restart = axienet_pcs_an_restart,
+};
+
+static struct phylink_pcs *axienet_mac_select_pcs(struct phylink_config *config,
+						  phy_interface_t interface)
 {
 	struct net_device *ndev = to_net_dev(config->dev);
 	struct axienet_local *lp = netdev_priv(ndev);
-	int ret;
 
-	switch (state->interface) {
-	case PHY_INTERFACE_MODE_SGMII:
-	case PHY_INTERFACE_MODE_1000BASEX:
-		ret = phylink_mii_c22_pcs_config(lp->pcs_phy, mode,
-						 state->interface,
-						 state->advertising);
-		if (ret < 0)
-			netdev_warn(ndev, "Failed to configure PCS: %d\n",
-				    ret);
-		break;
+	if (interface == PHY_INTERFACE_MODE_1000BASEX ||
+	    interface ==  PHY_INTERFACE_MODE_SGMII)
+		return &lp->pcs;
 
-	default:
-		break;
-	}
+	return NULL;
+}
+
+static void axienet_mac_config(struct phylink_config *config, unsigned int mode,
+			       const struct phylink_link_state *state)
+{
+	/* nothing meaningful to do */
 }
 
 static void axienet_mac_link_down(struct phylink_config *config,
@@ -1629,9 +1626,7 @@ static void axienet_mac_link_up(struct phylink_config *config,
 
 static const struct phylink_mac_ops axienet_phylink_ops = {
 	.validate = phylink_generic_validate,
-	.mac_pcs_get_state = axienet_mac_pcs_get_state,
-	.mac_an_restart = axienet_mac_an_restart,
-	.mac_prepare = axienet_mac_prepare,
+	.mac_select_pcs = axienet_mac_select_pcs,
 	.mac_config = axienet_mac_config,
 	.mac_link_down = axienet_mac_link_down,
 	.mac_link_up = axienet_mac_link_up,
@@ -2040,12 +2035,12 @@ static int axienet_probe(struct platform_device *pdev)
 			ret = -EPROBE_DEFER;
 			goto cleanup_mdio;
 		}
-		lp->phylink_config.pcs_poll = true;
+		lp->pcs.ops = &axienet_pcs_ops;
+		lp->pcs.poll = true;
 	}
 
 	lp->phylink_config.dev = &ndev->dev;
 	lp->phylink_config.type = PHYLINK_NETDEV;
-	lp->phylink_config.legacy_pre_march2020 = true;
 	lp->phylink_config.mac_capabilities = MAC_SYM_PAUSE | MAC_ASYM_PAUSE |
 		MAC_10FD | MAC_100FD | MAC_1000FD;
 
-- 
2.30.2

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

Re: [PATCH net-next 2/7] net: phylink: add pcs_validate() method

[Sean Anderson]

On 12/14/21 6:27 PM, Russell King (Oracle) wrote:
> On Tue, Dec 14, 2021 at 02:49:13PM -0500, Sean Anderson wrote:
>> Hi Russell,
>>
>> On 12/14/21 9:48 AM, Russell King (Oracle) wrote:
>> > Add a hook for PCS to validate the link parameters. This avoids MAC
>> > drivers having to have knowledge of their PCS in their validate()
>> > method, thereby allowing several MAC drivers to be simplfied.
>> >
>> > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
>> > ---
>> >   drivers/net/phy/phylink.c | 31 +++++++++++++++++++++++++++++++
>> >   include/linux/phylink.h   | 20 ++++++++++++++++++++
>> >   2 files changed, 51 insertions(+)
>> >
>> > diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
>> > index c7035d65e159..420201858564 100644
>> > --- a/drivers/net/phy/phylink.c
>> > +++ b/drivers/net/phy/phylink.c
>> > @@ -424,13 +424,44 @@ static int phylink_validate_mac_and_pcs(struct phylink *pl,
>> >   					struct phylink_link_state *state)
>> >   {
>> >   	struct phylink_pcs *pcs;
>> > +	int ret;
>> >
>> > +	/* Get the PCS for this interface mode */
>> >   	if (pl->mac_ops->mac_select_pcs) {
>> >   		pcs = pl->mac_ops->mac_select_pcs(pl->config, state->interface);
>> >   		if (IS_ERR(pcs))
>> >   			return PTR_ERR(pcs);
>> > +	} else {
>> > +		pcs = pl->pcs;
>> > +	}
>> > +
>> > +	if (pcs) {
>> > +		/* The PCS, if present, must be setup before phylink_create()
>> > +		 * has been called. If the ops is not initialised, print an
>> > +		 * error and backtrace rather than oopsing the kernel.
>> > +		 */
>> > +		if (!pcs->ops) {
>> > +			phylink_err(pl, "interface %s: uninitialised PCS\n",
>> > +				    phy_modes(state->interface));
>> > +			dump_stack();
>> > +			return -EINVAL;
>> > +		}
>> > +
>> > +		/* Validate the link parameters with the PCS */
>> > +		if (pcs->ops->pcs_validate) {
>> > +			ret = pcs->ops->pcs_validate(pcs, supported, state);
>>
>> I wonder if we can add a pcs->supported_interfaces. That would let me
>> write something like
>
> I have two arguments against that:
>
> 1) Given that .mac_select_pcs should not return a PCS that is not
>     appropriate for the provided state->interface, I don't see what
>     use having a supported_interfaces member in the PCS would give.
>     All that phylink would end up doing is validating that the MAC
>     was giving us a sane PCS.

The MAC may not know what the PCS can support. For example, the xilinx
PCS/PMA can be configured to support 1000BASE-X, SGMII, both, or
neither. How else should the mac find out what is supported?

> 2) In the case of a static PCS (in other words, one attached just
>     after phylink_create_pcs()) the PCS is known at creation time,
>     so limiting phylink_config.supported_interfaces according to the
>     single attached interface seems sane, rather than phylink having
>     to repeatedly recalculate the bitwise-and between both
>     supported_interface masks.
>
>> static int xilinx_pcs_validate(struct phylink_pcs *pcs,
>> 			       unsigned long *supported,
>> 			       struct phylink_link_state *state)
>> {
>> 	__ETHTOOL_DECLARE_LINK_MODE_MASK(mask) = { 0, };
>>
>> 	phylink_set_port_modes(mask);
>> 	phylink_set(mask, Autoneg);
>> 	phylink_get_linkmodes(mask, state->interface,
>> 			      MAC_10FD | MAC_100FD | MAC_1000FD);
>>
>> 	linkmode_and(supported, supported, mask);
>> }
>
> This would be buggy - doesn't the PCS allow pause frames through?

Yes. I noticed this after writing my above email :)

> I already have a conversion for axienet in my tree, and it doesn't
> need a pcs_validate() implementation. I'll provide it below.
>
>> And of course, the above could become phylink_pcs_validate_generic with
>> the addition of a pcs->pcs_capabilities member.
>>
>> The only wrinkle is that we need to handle PHY_INTERFACE_MODE_NA,
>> because of the pcs = pl->pcs assignment above. This would require doing
>> the phylink_validate_any dance again.
>
> Why do you think PHY_INTERFACE_MODE_NA needs handling? If this is not
> set in phylink_config.supported_interfaces (which it should never be)
> then none of the validation will be called with this.

If the MAC has no supported_interfaces and calls phylink_set_pcs, but
does not implement mac_select_pcs, then you can have something like

     phylink_validate(NA)
         phylink_validate_mac_and_pcs(NA)
             pcs = pl->pcs;
             pcs->ops->pcs_validate(NA)
                 phylink_get_linkmodes(NA)
                 /* returns just Pause and Asym_Pause linkmodes */
             /* nonzero, so pcs_validate thinks it's fine */
     /* phylink_validate returns 0, but there are no valid interfaces */

> The special PHY_INTERFACE_MODE_NA meaning "give us everything you have"
> is something I want to get rid of, and is something that I am already
> explicitly not supporting for pcs_validate(). It doesn't work with the
> mac_select_pcs() model, since that can't return all PCS that may be
> used.
>
>> 	if (state->interface == PHY_INTERFACE_MODE_NA)
>> 		return -EINVAL;
>>
>> at the top of phylink_pcs_validate_generic (perhaps with a warning).
>> That would catch any MACs who use a PCS which wants the MAC to have
>> supported_interfaces.
>
> ... which could be too late.

You can't detect this in advance, since a MAC can choose to attach
whatever PCS it wants at any time. So all you can do is warn about it so
people report it as a bug instead of wondering why their ethernet won't
configure.

>> > +			if (ret < 0 || phylink_is_empty_linkmode(supported))
>> > +				return -EINVAL;
>> > +
>> > +			/* Ensure the advertising mask is a subset of the
>> > +			 * supported mask.
>> > +			 */
>> > +			linkmode_and(state->advertising, state->advertising,
>> > +				     supported);
>> > +		}
>> >   	}
>> >
>> > +	/* Then validate the link parameters with the MAC */
>> >   	pl->mac_ops->validate(pl->config, supported, state);
>>
>> Shouldn't the PCS stuff happen here? Later in the series, you do things
>> like
>>
>> 	if (phy_interface_mode_is_8023z(state->interface) &&
>> 	    !phylink_test(state->advertising, Autoneg))
>> 		return -EINVAL;
>>
>> but there's nothing to stop a mac validate from coming along and saying
>> "we don't support autonegotiation".
>
> How is autonegotiation a property of the MAC when there is a PCS?
> In what situation is autonegotiation terminated at the MAC when
> there is a PCS present?

*shrug* it doesn't make a difference really as long as the MAC and PCS
play nice. But validate works by masking out bits, so you can only
really test for a bit after everyone has gotten their chance to veto
things. Which is why I think it is strange that the PCS check comes
first.

--Sean

> The only case I can think of is where the PCS is tightly tied to the
> MAC, and in that case you end up with a choice whether or not to model
> a PCS in software. This is the case with mvneta and mvpp2 - there is
> no separation of the MAC and PCS in the hardware register design. There
> is one register that controls pause/duplex advertisement and speeds
> irrespective of the PHY interface, whether the interface mode to the
> external world is 1000BASE-X, SGMII, QSGMII, RGMII etc. mvpp2 is
> slightly different in that it re-uses the GMAC design from mvneta for
> speeds <= 2.5G, and an entirely separate XLG implementation for 5G
> and 10G. Here, we model these as two separate PCS that we choose
> between depending on the interface.
>

Re: [PATCH net-next 2/7] net: phylink: add pcs_validate() method

[Russell King (Oracle)]

On Tue, Dec 14, 2021 at 06:54:16PM -0500, Sean Anderson wrote:
> On 12/14/21 6:27 PM, Russell King (Oracle) wrote:
> > On Tue, Dec 14, 2021 at 02:49:13PM -0500, Sean Anderson wrote:
> > > Hi Russell,
> > > 
> > > On 12/14/21 9:48 AM, Russell King (Oracle) wrote:
> > > > Add a hook for PCS to validate the link parameters. This avoids MAC
> > > > drivers having to have knowledge of their PCS in their validate()
> > > > method, thereby allowing several MAC drivers to be simplfied.
> > > >
> > > > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> > > > ---
> > > >   drivers/net/phy/phylink.c | 31 +++++++++++++++++++++++++++++++
> > > >   include/linux/phylink.h   | 20 ++++++++++++++++++++
> > > >   2 files changed, 51 insertions(+)
> > > >
> > > > diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
> > > > index c7035d65e159..420201858564 100644
> > > > --- a/drivers/net/phy/phylink.c
> > > > +++ b/drivers/net/phy/phylink.c
> > > > @@ -424,13 +424,44 @@ static int phylink_validate_mac_and_pcs(struct phylink *pl,
> > > >   					struct phylink_link_state *state)
> > > >   {
> > > >   	struct phylink_pcs *pcs;
> > > > +	int ret;
> > > >
> > > > +	/* Get the PCS for this interface mode */
> > > >   	if (pl->mac_ops->mac_select_pcs) {
> > > >   		pcs = pl->mac_ops->mac_select_pcs(pl->config, state->interface);
> > > >   		if (IS_ERR(pcs))
> > > >   			return PTR_ERR(pcs);
> > > > +	} else {
> > > > +		pcs = pl->pcs;
> > > > +	}
> > > > +
> > > > +	if (pcs) {
> > > > +		/* The PCS, if present, must be setup before phylink_create()
> > > > +		 * has been called. If the ops is not initialised, print an
> > > > +		 * error and backtrace rather than oopsing the kernel.
> > > > +		 */
> > > > +		if (!pcs->ops) {
> > > > +			phylink_err(pl, "interface %s: uninitialised PCS\n",
> > > > +				    phy_modes(state->interface));
> > > > +			dump_stack();
> > > > +			return -EINVAL;
> > > > +		}
> > > > +
> > > > +		/* Validate the link parameters with the PCS */
> > > > +		if (pcs->ops->pcs_validate) {
> > > > +			ret = pcs->ops->pcs_validate(pcs, supported, state);
> > > 
> > > I wonder if we can add a pcs->supported_interfaces. That would let me
> > > write something like
> > 
> > I have two arguments against that:
> > 
> > 1) Given that .mac_select_pcs should not return a PCS that is not
> >     appropriate for the provided state->interface, I don't see what
> >     use having a supported_interfaces member in the PCS would give.
> >     All that phylink would end up doing is validating that the MAC
> >     was giving us a sane PCS.
> 
> The MAC may not know what the PCS can support. For example, the xilinx
> PCS/PMA can be configured to support 1000BASE-X, SGMII, both, or
> neither. How else should the mac find out what is supported?

I'll reply by asking a more relevant question at this point.

If we've asked for a PCS for 1000BASE-X via .mac_select_pcs() and a
PCS is returned that does not support 1000BASE-X, what happens then?
The system level says 1000BASE-X was supported when it isn't...
That to me sounds like bug.

> > 2) In the case of a static PCS (in other words, one attached just
> >     after phylink_create_pcs()) the PCS is known at creation time,
> >     so limiting phylink_config.supported_interfaces according to the
> >     single attached interface seems sane, rather than phylink having
> >     to repeatedly recalculate the bitwise-and between both
> >     supported_interface masks.
> > 
> > > static int xilinx_pcs_validate(struct phylink_pcs *pcs,
> > > 			       unsigned long *supported,
> > > 			       struct phylink_link_state *state)
> > > {
> > > 	__ETHTOOL_DECLARE_LINK_MODE_MASK(mask) = { 0, };
> > > 
> > > 	phylink_set_port_modes(mask);
> > > 	phylink_set(mask, Autoneg);
> > > 	phylink_get_linkmodes(mask, state->interface,
> > > 			      MAC_10FD | MAC_100FD | MAC_1000FD);
> > > 
> > > 	linkmode_and(supported, supported, mask);
> > > }
> > 
> > This would be buggy - doesn't the PCS allow pause frames through?
> 
> Yes. I noticed this after writing my above email :)
> 
> > I already have a conversion for axienet in my tree, and it doesn't
> > need a pcs_validate() implementation. I'll provide it below.
> > 
> > > And of course, the above could become phylink_pcs_validate_generic with
> > > the addition of a pcs->pcs_capabilities member.
> > > 
> > > The only wrinkle is that we need to handle PHY_INTERFACE_MODE_NA,
> > > because of the pcs = pl->pcs assignment above. This would require doing
> > > the phylink_validate_any dance again.
> > 
> > Why do you think PHY_INTERFACE_MODE_NA needs handling? If this is not
> > set in phylink_config.supported_interfaces (which it should never be)
> > then none of the validation will be called with this.
> 
> If the MAC has no supported_interfaces and calls phylink_set_pcs, but
> does not implement mac_select_pcs, then you can have something like
> 
>     phylink_validate(NA)
>         phylink_validate_mac_and_pcs(NA)
>             pcs = pl->pcs;
>             pcs->ops->pcs_validate(NA)
>                 phylink_get_linkmodes(NA)
>                 /* returns just Pause and Asym_Pause linkmodes */
>             /* nonzero, so pcs_validate thinks it's fine */
>     /* phylink_validate returns 0, but there are no valid interfaces */

No, you don't end up in that situation, because phylink_validate() will
not return 0. It will return -EINVAL. We are not checking for an empty
supported mask, we are checking for a supported mask that contains no
linkmodes - this is an important difference between linkmode_empty()
and phylink_is_empty_linkmode(). The former checks for the linkmode
bitmap containing all zeros, the latter doesn't care about the media
bits, autoneg, pause or asympause linkmode bits. If all other bits are
zero, it returns true, causing phylink_validate_mac_and_pcs() to return
-EINVAL.

> > The special PHY_INTERFACE_MODE_NA meaning "give us everything you have"
> > is something I want to get rid of, and is something that I am already
> > explicitly not supporting for pcs_validate(). It doesn't work with the
> > mac_select_pcs() model, since that can't return all PCS that may be
> > used.
> > 
> > > 	if (state->interface == PHY_INTERFACE_MODE_NA)
> > > 		return -EINVAL;
> > > 
> > > at the top of phylink_pcs_validate_generic (perhaps with a warning).
> > > That would catch any MACs who use a PCS which wants the MAC to have
> > > supported_interfaces.
> > 
> > ... which could be too late.
> 
> You can't detect this in advance, since a MAC can choose to attach
> whatever PCS it wants at any time. So all you can do is warn about it so
> people report it as a bug instead of wondering why their ethernet won't
> configure.

As I say above, I don't see there's a problem here - and I think you've
mistaken the behaviour of phylink_is_empty_linkmode().

> 
> > > > +			if (ret < 0 || phylink_is_empty_linkmode(supported))
> > > > +				return -EINVAL;
> > > > +
> > > > +			/* Ensure the advertising mask is a subset of the
> > > > +			 * supported mask.
> > > > +			 */
> > > > +			linkmode_and(state->advertising, state->advertising,
> > > > +				     supported);
> > > > +		}
> > > >   	}
> > > >
> > > > +	/* Then validate the link parameters with the MAC */
> > > >   	pl->mac_ops->validate(pl->config, supported, state);
> > > 
> > > Shouldn't the PCS stuff happen here? Later in the series, you do things
> > > like
> > > 
> > > 	if (phy_interface_mode_is_8023z(state->interface) &&
> > > 	    !phylink_test(state->advertising, Autoneg))
> > > 		return -EINVAL;
> > > 
> > > but there's nothing to stop a mac validate from coming along and saying
> > > "we don't support autonegotiation".
> > 
> > How is autonegotiation a property of the MAC when there is a PCS?
> > In what situation is autonegotiation terminated at the MAC when
> > there is a PCS present?
> 
> *shrug* it doesn't make a difference really as long as the MAC and PCS
> play nice. But validate works by masking out bits, so you can only
> really test for a bit after everyone has gotten their chance to veto
> things. Which is why I think it is strange that the PCS check comes
> first.

For the explicit case you are highlighting (autoneg), please give an
example where both the PCS and MAC would get to "vote" on this bit.
Please explain how the MAC would even be involved in autonegotiation.

I'm not going to say that this model is perfect, because it isn't.
It is adequate for the purposes we need to solve to move the code
forwards, and I believe it will allow us to elimate the mac_ops
.validate method entirely in a release or two.

Once that is done, we will rely on mac_capabilities to tell us what
the MAC supports, which is really all that we need the MAC to be
telling us. This will become important when we e.g. properly model
rate adapting PCS.

We can't get close to a model that allows us to do that right now
because the .validate method prevents that because that deals with
media linkmodes, rather than just the capabilities of the MAC. Our
only option right now would be to completely avoid calling the
.validate method if we know we have a PCS and completely ignore
MAC capabilities.

This is an evolutionary step sorting out some of the issues. I'm
very sure that there will be things it doesn't do very well
identified, and we will need to address those later.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

Re: [PATCH net-next 1/7] net: phylink: add mac_select_pcs() method to phylink_mac_ops

[Jakub Kicinski]

On Tue, 14 Dec 2021 14:48:05 +0000 Russell King (Oracle) wrote:
> +/**
> + * @mac_select_pcs: Select a PCS for the interface mode.

nit: no '@' in front of the function name

> + * @config: a pointer to a &struct phylink_config.
> + * @interface: PHY interface mode for PCS
> + *
> + * Return the &struct phylink_pcs for the specified interface mode, or
> + * NULL if none is required, or an error pointer on error.
> + *
> + * This must not modify any state. It is used to query which PCS should
> + * be used. Phylink will use this during validation to ensure that the
> + * configuration is valid, and when setting a configuration to internally
> + * set the PCS that will be used.
> + */
> +struct phylink_pcs *mac_select_pcs(struct phylink_config *config,
> +				   phy_interface_t interface);

Re: [PATCH net-next 2/7] net: phylink: add pcs_validate() method

[Sean Anderson]

On 12/14/21 7:32 PM, Russell King (Oracle) wrote:
> On Tue, Dec 14, 2021 at 06:54:16PM -0500, Sean Anderson wrote:
>> On 12/14/21 6:27 PM, Russell King (Oracle) wrote:
>> > On Tue, Dec 14, 2021 at 02:49:13PM -0500, Sean Anderson wrote:
>> > > Hi Russell,
>> > >
>> > > On 12/14/21 9:48 AM, Russell King (Oracle) wrote:
>> > > > Add a hook for PCS to validate the link parameters. This avoids MAC
>> > > > drivers having to have knowledge of their PCS in their validate()
>> > > > method, thereby allowing several MAC drivers to be simplfied.
>> > > >
>> > > > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
>> > > > ---
>> > > >   drivers/net/phy/phylink.c | 31 +++++++++++++++++++++++++++++++
>> > > >   include/linux/phylink.h   | 20 ++++++++++++++++++++
>> > > >   2 files changed, 51 insertions(+)
>> > > >
>> > > > diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
>> > > > index c7035d65e159..420201858564 100644
>> > > > --- a/drivers/net/phy/phylink.c
>> > > > +++ b/drivers/net/phy/phylink.c
>> > > > @@ -424,13 +424,44 @@ static int phylink_validate_mac_and_pcs(struct phylink *pl,
>> > > >   					struct phylink_link_state *state)
>> > > >   {
>> > > >   	struct phylink_pcs *pcs;
>> > > > +	int ret;
>> > > >
>> > > > +	/* Get the PCS for this interface mode */
>> > > >   	if (pl->mac_ops->mac_select_pcs) {
>> > > >   		pcs = pl->mac_ops->mac_select_pcs(pl->config, state->interface);
>> > > >   		if (IS_ERR(pcs))
>> > > >   			return PTR_ERR(pcs);
>> > > > +	} else {
>> > > > +		pcs = pl->pcs;
>> > > > +	}
>> > > > +
>> > > > +	if (pcs) {
>> > > > +		/* The PCS, if present, must be setup before phylink_create()
>> > > > +		 * has been called. If the ops is not initialised, print an
>> > > > +		 * error and backtrace rather than oopsing the kernel.
>> > > > +		 */
>> > > > +		if (!pcs->ops) {
>> > > > +			phylink_err(pl, "interface %s: uninitialised PCS\n",
>> > > > +				    phy_modes(state->interface));
>> > > > +			dump_stack();
>> > > > +			return -EINVAL;
>> > > > +		}
>> > > > +
>> > > > +		/* Validate the link parameters with the PCS */
>> > > > +		if (pcs->ops->pcs_validate) {
>> > > > +			ret = pcs->ops->pcs_validate(pcs, supported, state);
>> > >
>> > > I wonder if we can add a pcs->supported_interfaces. That would let me
>> > > write something like
>> >
>> > I have two arguments against that:
>> >
>> > 1) Given that .mac_select_pcs should not return a PCS that is not
>> >     appropriate for the provided state->interface, I don't see what
>> >     use having a supported_interfaces member in the PCS would give.
>> >     All that phylink would end up doing is validating that the MAC
>> >     was giving us a sane PCS.
>>
>> The MAC may not know what the PCS can support. For example, the xilinx
>> PCS/PMA can be configured to support 1000BASE-X, SGMII, both, or
>> neither. How else should the mac find out what is supported?
>
> I'll reply by asking a more relevant question at this point.
>
> If we've asked for a PCS for 1000BASE-X via .mac_select_pcs() and a
> PCS is returned that does not support 1000BASE-X, what happens then?
> The system level says 1000BASE-X was supported when it isn't...
> That to me sounds like bug.

Well, there are two ways to approach this, IMO, and both involve some
kind of supported_interfaces bitmap. The underlying constraint here is
that the MAC doesn't really know/care at compile-time what the PCS
supports.

- The MAC always returns the external PCS, since that is what the user
   configured. In this case, the PCS is responsible for ensuring that the
   interface is supported. If phylink does not do this check, then it
   must be done in pcs_validate().
- The MAC inspects the PCS's supported_interfaces bitmap, and only
   returns it from mac_select_pcs if it matches.

Sure, if the user says

	pcs-handle = <&my_1000basex_only_pcs>;
	phy-mode = "sgmii";

then this is a misconfiguration, but it is something which we have to
catch, and which the MAC shouldn't detect without additional
information.

>> > 2) In the case of a static PCS (in other words, one attached just
>> >     after phylink_create_pcs()) the PCS is known at creation time,
>> >     so limiting phylink_config.supported_interfaces according to the
>> >     single attached interface seems sane, rather than phylink having
>> >     to repeatedly recalculate the bitwise-and between both
>> >     supported_interface masks.
>> >
>> > > static int xilinx_pcs_validate(struct phylink_pcs *pcs,
>> > > 			       unsigned long *supported,
>> > > 			       struct phylink_link_state *state)
>> > > {
>> > > 	__ETHTOOL_DECLARE_LINK_MODE_MASK(mask) = { 0, };
>> > >
>> > > 	phylink_set_port_modes(mask);
>> > > 	phylink_set(mask, Autoneg);
>> > > 	phylink_get_linkmodes(mask, state->interface,
>> > > 			      MAC_10FD | MAC_100FD | MAC_1000FD);
>> > >
>> > > 	linkmode_and(supported, supported, mask);
>> > > }
>> >
>> > This would be buggy - doesn't the PCS allow pause frames through?
>>
>> Yes. I noticed this after writing my above email :)
>>
>> > I already have a conversion for axienet in my tree, and it doesn't
>> > need a pcs_validate() implementation. I'll provide it below.
>> >
>> > > And of course, the above could become phylink_pcs_validate_generic with
>> > > the addition of a pcs->pcs_capabilities member.
>> > >
>> > > The only wrinkle is that we need to handle PHY_INTERFACE_MODE_NA,
>> > > because of the pcs = pl->pcs assignment above. This would require doing
>> > > the phylink_validate_any dance again.
>> >
>> > Why do you think PHY_INTERFACE_MODE_NA needs handling? If this is not
>> > set in phylink_config.supported_interfaces (which it should never be)
>> > then none of the validation will be called with this.
>>
>> If the MAC has no supported_interfaces and calls phylink_set_pcs, but
>> does not implement mac_select_pcs, then you can have something like
>>
>>     phylink_validate(NA)
>>         phylink_validate_mac_and_pcs(NA)
>>             pcs = pl->pcs;
>>             pcs->ops->pcs_validate(NA)
>>                 phylink_get_linkmodes(NA)
>>                 /* returns just Pause and Asym_Pause linkmodes */
>>             /* nonzero, so pcs_validate thinks it's fine */
>>     /* phylink_validate returns 0, but there are no valid interfaces */
>
> No, you don't end up in that situation, because phylink_validate() will
> not return 0. It will return -EINVAL. We are not checking for an empty
> supported mask, we are checking for a supported mask that contains no
> linkmodes - this is an important difference between linkmode_empty()
> and phylink_is_empty_linkmode(). The former checks for the linkmode
> bitmap containing all zeros, the latter doesn't care about the media
> bits, autoneg, pause or asympause linkmode bits. If all other bits are
> zero, it returns true, causing phylink_validate_mac_and_pcs() to return
> -EINVAL.

OK, then there should be no issue here.

--Sean

Re: [PATCH net-next 2/7] net: phylink: add pcs_validate() method

[Russell King (Oracle)]

On Thu, Dec 16, 2021 at 10:42:08AM -0500, Sean Anderson wrote:
> 
> 
> On 12/14/21 7:32 PM, Russell King (Oracle) wrote:
> > On Tue, Dec 14, 2021 at 06:54:16PM -0500, Sean Anderson wrote:
> > > On 12/14/21 6:27 PM, Russell King (Oracle) wrote:
> > > > On Tue, Dec 14, 2021 at 02:49:13PM -0500, Sean Anderson wrote:
> > > > > Hi Russell,
> > > > >
> > > > > On 12/14/21 9:48 AM, Russell King (Oracle) wrote:
> > > > > > Add a hook for PCS to validate the link parameters. This avoids MAC
> > > > > > drivers having to have knowledge of their PCS in their validate()
> > > > > > method, thereby allowing several MAC drivers to be simplfied.
> > > > > >
> > > > > > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> > > > > > ---
> > > > > >   drivers/net/phy/phylink.c | 31 +++++++++++++++++++++++++++++++
> > > > > >   include/linux/phylink.h   | 20 ++++++++++++++++++++
> > > > > >   2 files changed, 51 insertions(+)
> > > > > >
> > > > > > diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
> > > > > > index c7035d65e159..420201858564 100644
> > > > > > --- a/drivers/net/phy/phylink.c
> > > > > > +++ b/drivers/net/phy/phylink.c
> > > > > > @@ -424,13 +424,44 @@ static int phylink_validate_mac_and_pcs(struct phylink *pl,
> > > > > >   					struct phylink_link_state *state)
> > > > > >   {
> > > > > >   	struct phylink_pcs *pcs;
> > > > > > +	int ret;
> > > > > >
> > > > > > +	/* Get the PCS for this interface mode */
> > > > > >   	if (pl->mac_ops->mac_select_pcs) {
> > > > > >   		pcs = pl->mac_ops->mac_select_pcs(pl->config, state->interface);
> > > > > >   		if (IS_ERR(pcs))
> > > > > >   			return PTR_ERR(pcs);
> > > > > > +	} else {
> > > > > > +		pcs = pl->pcs;
> > > > > > +	}
> > > > > > +
> > > > > > +	if (pcs) {
> > > > > > +		/* The PCS, if present, must be setup before phylink_create()
> > > > > > +		 * has been called. If the ops is not initialised, print an
> > > > > > +		 * error and backtrace rather than oopsing the kernel.
> > > > > > +		 */
> > > > > > +		if (!pcs->ops) {
> > > > > > +			phylink_err(pl, "interface %s: uninitialised PCS\n",
> > > > > > +				    phy_modes(state->interface));
> > > > > > +			dump_stack();
> > > > > > +			return -EINVAL;
> > > > > > +		}
> > > > > > +
> > > > > > +		/* Validate the link parameters with the PCS */
> > > > > > +		if (pcs->ops->pcs_validate) {
> > > > > > +			ret = pcs->ops->pcs_validate(pcs, supported, state);
> > > > >
> > > > > I wonder if we can add a pcs->supported_interfaces. That would let me
> > > > > write something like
> > > >
> > > > I have two arguments against that:
> > > >
> > > > 1) Given that .mac_select_pcs should not return a PCS that is not
> > > >     appropriate for the provided state->interface, I don't see what
> > > >     use having a supported_interfaces member in the PCS would give.
> > > >     All that phylink would end up doing is validating that the MAC
> > > >     was giving us a sane PCS.
> > > 
> > > The MAC may not know what the PCS can support. For example, the xilinx
> > > PCS/PMA can be configured to support 1000BASE-X, SGMII, both, or
> > > neither. How else should the mac find out what is supported?
> > 
> > I'll reply by asking a more relevant question at this point.
> > 
> > If we've asked for a PCS for 1000BASE-X via .mac_select_pcs() and a
> > PCS is returned that does not support 1000BASE-X, what happens then?
> > The system level says 1000BASE-X was supported when it isn't...
> > That to me sounds like bug.
> 
> Well, there are two ways to approach this, IMO, and both involve some
> kind of supported_interfaces bitmap. The underlying constraint here is
> that the MAC doesn't really know/care at compile-time what the PCS
> supports.
> 
> - The MAC always returns the external PCS, since that is what the user
>   configured. In this case, the PCS is responsible for ensuring that the
>   interface is supported. If phylink does not do this check, then it
>   must be done in pcs_validate().
> - The MAC inspects the PCS's supported_interfaces bitmap, and only
>   returns it from mac_select_pcs if it matches.

Yes - we can do these sorts of things later if it turns out there is
a requirement to do so. At the moment, having been through all the
drivers recently, I don't see the need for it yet.

The only driver that may come close is xpcs, and the patches I've
proposed there don't need it - I just populate the PCS support 
by calling into xpcs.

-- 
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