[PATCH net-next v2 0/3] net: phylink: simplify SFP PHY attachment

[PATCH net-next v2 0/3] net: phylink: simplify SFP PHY attachment

[Russell King (Oracle)]

Hi,

These two patches simplify how we attach SFP PHYs.

The first patch notices that at the two sites where we call
sfp_select_interface(), if that fails, we always print the same error.
Move this into its own function.

The second patch adds an additional level of validation, checking that
the returned interface is one that is supported by the MAC/PCS.

The last patch simplifies how SFP PHYs are attached, reducing the
number of times that we do validation in this path.

 drivers/net/phy/phylink.c | 83 ++++++++++++++++++++++++-----------------------
 1 file changed, 42 insertions(+), 41 deletions(-)

Changes since v1:
 - Fixed build warning.
 - Added r-b/t-b from Maxime.

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[PATCH net-next v2 1/3] net: phylink: add common validation for sfp_select_interface()

[Russell King (Oracle)]

Whenever we call sfp_select_interface(), we check the returned value
and print an error. There are two cases where this happens with the
same message. Provide a common function to do this.

Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 drivers/net/phy/phylink.c | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index b5870f8666ac..62d347d1112c 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -2415,6 +2415,21 @@ int phylink_ethtool_set_wol(struct phylink *pl, struct ethtool_wolinfo *wol)
 }
 EXPORT_SYMBOL_GPL(phylink_ethtool_set_wol);
 
+static phy_interface_t phylink_sfp_select_interface(struct phylink *pl,
+						const unsigned long *link_modes)
+{
+	phy_interface_t interface;
+
+	interface = sfp_select_interface(pl->sfp_bus, link_modes);
+	if (interface == PHY_INTERFACE_MODE_NA)
+		phylink_err(pl,
+			    "selection of interface failed, advertisement %*pb\n",
+			    __ETHTOOL_LINK_MODE_MASK_NBITS,
+			    link_modes);
+
+	return interface;
+}
+
 static void phylink_merge_link_mode(unsigned long *dst, const unsigned long *b)
 {
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(mask);
@@ -2597,15 +2612,10 @@ int phylink_ethtool_ksettings_set(struct phylink *pl,
 	 * link can be configured correctly.
 	 */
 	if (pl->sfp_bus) {
-		config.interface = sfp_select_interface(pl->sfp_bus,
+		config.interface = phylink_sfp_select_interface(pl,
 							config.advertising);
-		if (config.interface == PHY_INTERFACE_MODE_NA) {
-			phylink_err(pl,
-				    "selection of interface failed, advertisement %*pb\n",
-				    __ETHTOOL_LINK_MODE_MASK_NBITS,
-				    config.advertising);
+		if (config.interface == PHY_INTERFACE_MODE_NA)
 			return -EINVAL;
-		}
 
 		/* Revalidate with the selected interface */
 		linkmode_copy(support, pl->supported);
@@ -3234,13 +3244,9 @@ static int phylink_sfp_config_phy(struct phylink *pl, u8 mode,
 		return ret;
 	}
 
-	iface = sfp_select_interface(pl->sfp_bus, config.advertising);
-	if (iface == PHY_INTERFACE_MODE_NA) {
-		phylink_err(pl,
-			    "selection of interface failed, advertisement %*pb\n",
-			    __ETHTOOL_LINK_MODE_MASK_NBITS, config.advertising);
+	iface = phylink_sfp_select_interface(pl, config.advertising);
+	if (iface == PHY_INTERFACE_MODE_NA)
 		return -EINVAL;
-	}
 
 	config.interface = iface;
 	linkmode_copy(support1, support);
-- 
2.30.2

[PATCH net-next v2 2/3] net: phylink: validate sfp_select_interface() returned interface

[Russell King (Oracle)]

Validate that the returned interface from sfp_select_interface() is
supportable by the MAC/PCS. If it isn't, print an error and return
the NA interface type. This is a preparatory step to reorganising
how a PHY on a SFP module is handled.

Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 drivers/net/phy/phylink.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 62d347d1112c..4049d85cb477 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -2421,11 +2421,22 @@ static phy_interface_t phylink_sfp_select_interface(struct phylink *pl,
 	phy_interface_t interface;
 
 	interface = sfp_select_interface(pl->sfp_bus, link_modes);
-	if (interface == PHY_INTERFACE_MODE_NA)
+	if (interface == PHY_INTERFACE_MODE_NA) {
 		phylink_err(pl,
 			    "selection of interface failed, advertisement %*pb\n",
 			    __ETHTOOL_LINK_MODE_MASK_NBITS,
 			    link_modes);
+		return interface;
+	}
+
+	if (!test_bit(interface, pl->config->supported_interfaces)) {
+		phylink_err(pl,
+			    "selection of interface failed, SFP selected %s (%u) but MAC supports %*pbl\n",
+			    phy_modes(interface), interface,
+			    (int)PHY_INTERFACE_MODE_MAX,
+			    pl->config->supported_interfaces);
+		return PHY_INTERFACE_MODE_NA;
+	}
 
 	return interface;
 }
-- 
2.30.2

[PATCH net-next v2 3/3] net: phylink: simplify how SFP PHYs are attached

[Russell King (Oracle)]

There are a few issues with how SFP PHYs are attached:

a) The phylink_sfp_connect_phy() and phylink_sfp_config_phy() code
   validates the configuration three times:

1. To discover the support/advertising masks that the PHY/PCS/MAC
   can support in order to select an interface.
2. To validate the selected interface.
3. When the PHY is brought up after being attached, another validation
   is done.

   This is needlessly complex.

b) The configuration is set prior to the PHY being attached, which
   means we don't have the PHY available in phylink_major_config()
   for phylink_pcs_neg_mode() to make decisions upon.

We have already added an extra step to validate the selected interface,
so we can now move the attachment and bringup of the PHY earlier,
inside phylink_sfp_config_phy(). This results in the validation at
step 2 above becoming entirely unnecessary, so remove that too.

Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 drivers/net/phy/phylink.c | 44 +++++++++++++--------------------------
 1 file changed, 14 insertions(+), 30 deletions(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 4049d85cb477..29206f72ab8b 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -3231,10 +3231,8 @@ static void phylink_sfp_set_config(struct phylink *pl, u8 mode,
 static int phylink_sfp_config_phy(struct phylink *pl, u8 mode,
 				  struct phy_device *phy)
 {
-	__ETHTOOL_DECLARE_LINK_MODE_MASK(support1);
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(support);
 	struct phylink_link_state config;
-	phy_interface_t iface;
 	int ret;
 
 	linkmode_copy(support, phy->supported);
@@ -3255,20 +3253,21 @@ static int phylink_sfp_config_phy(struct phylink *pl, u8 mode,
 		return ret;
 	}
 
-	iface = phylink_sfp_select_interface(pl, config.advertising);
-	if (iface == PHY_INTERFACE_MODE_NA)
+	config.interface = phylink_sfp_select_interface(pl, config.advertising);
+	if (config.interface == PHY_INTERFACE_MODE_NA)
 		return -EINVAL;
 
-	config.interface = iface;
-	linkmode_copy(support1, support);
-	ret = phylink_validate(pl, support1, &config);
-	if (ret) {
-		phylink_err(pl,
-			    "validation of %s/%s with support %*pb failed: %pe\n",
-			    phylink_an_mode_str(mode),
-			    phy_modes(config.interface),
-			    __ETHTOOL_LINK_MODE_MASK_NBITS, support,
-			    ERR_PTR(ret));
+	/* Attach the PHY so that the PHY is present when we do the major
+	 * configuration step.
+	 */
+	ret = phylink_attach_phy(pl, phy, config.interface);
+	if (ret < 0)
+		return ret;
+
+	/* This will validate the configuration for us. */
+	ret = phylink_bringup_phy(pl, phy, config.interface);
+	if (ret < 0) {
+		phy_detach(phy);
 		return ret;
 	}
 
@@ -3426,9 +3425,7 @@ static bool phylink_phy_no_inband(struct phy_device *phy)
 static int phylink_sfp_connect_phy(void *upstream, struct phy_device *phy)
 {
 	struct phylink *pl = upstream;
-	phy_interface_t interface;
 	u8 mode;
-	int ret;
 
 	/*
 	 * This is the new way of dealing with flow control for PHYs,
@@ -3449,20 +3446,7 @@ static int phylink_sfp_connect_phy(void *upstream, struct phy_device *phy)
 			  pl->config->supported_interfaces);
 
 	/* Do the initial configuration */
-	ret = phylink_sfp_config_phy(pl, mode, phy);
-	if (ret < 0)
-		return ret;
-
-	interface = pl->link_config.interface;
-	ret = phylink_attach_phy(pl, phy, interface);
-	if (ret < 0)
-		return ret;
-
-	ret = phylink_bringup_phy(pl, phy, interface);
-	if (ret)
-		phy_detach(phy);
-
-	return ret;
+	return phylink_sfp_config_phy(pl, mode, phy);
 }
 
 static void phylink_sfp_disconnect_phy(void *upstream,
-- 
2.30.2

Re: [PATCH net-next v2 0/3] net: phylink: simplify SFP PHY attachment

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 23 Oct 2024 14:41:17 +0100 you wrote:
> Hi,
> 
> These two patches simplify how we attach SFP PHYs.
> 
> The first patch notices that at the two sites where we call
> sfp_select_interface(), if that fails, we always print the same error.
> Move this into its own function.
> 
> [...]

Here is the summary with links:
  - [net-next,v2,1/3] net: phylink: add common validation for sfp_select_interface()
    https://git.kernel.org/netdev/net-next/c/280ed44982ff
  - [net-next,v2,2/3] net: phylink: validate sfp_select_interface() returned interface
    https://git.kernel.org/netdev/net-next/c/41caa7e81b97
  - [net-next,v2,3/3] net: phylink: simplify how SFP PHYs are attached
    https://git.kernel.org/netdev/net-next/c/25391e82ffe2

You are awesome, thank you!
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