[PATCH net-next v7 0/4] net: phy: bcm54811: PHY initialization

[PATCH net-next v7 0/4] net: phy: bcm54811: PHY initialization

[Kamil Horák - 2N]

Proper bcm54811 PHY driver initialization for MII-Lite.

The bcm54811 PHY in MLP package must be setup for MII-Lite interface
mode by software. Normally, the PHY to MAC interface is selected in
hardware by setting the bootstrap pins of the PHY. However, MII and
MII-Lite share the same hardware setup and must be distinguished by
software, setting appropriate bit in a configuration register.
The MII-Lite interface mode is non-standard one, defined by Broadcom
for some of their PHYs. The MII-Lite lightness consist in omitting
RXER, TXER, CRS and COL signals of the standard MII interface.
Absence of COL them makes half-duplex links modes impossible but
does not interfere with Broadcom's BroadR-Reach link modes, because
they are full-duplex only.
To do it in a clean way, MII-Lite must be introduced first, including
its limitation to link modes (no half-duplex), because it is a
prerequisite for the patch #3 of this series. The patch #4 does not
depend on MII-Lite directly but both #3 and #4 are necessary for 
bcm54811 to work properly without additional configuration steps to be
done - for example in the bootloader, before the kernel starts.

PATCH 1 - Add MII-Lite PHY interface mode as defined by Broadcom for
   their two-wire PHYs. It can be used with most Ethernet controllers
   under certain limitations (no half-duplex link modes etc.).

PATCH 2 - Add MII-Lite PHY interface type

PATCH 3 - Activation of MII-Lite interface mode on Broadcom bcm5481x
   PHYs

PATCH 4 - Initialize the BCM54811 PHY properly so that it conforms
   to the datasheet regarding a reserved bit in the LRE Control
   register, which must be written to zero after every device reset.
   Ignore the LDS capability bit in LRE Status register on bcm54811.

Changes in v2:
  - Applied reviewers' comments
  - Divided into more patches (separated common and Broadcom
   PHY specific code)

Changes in v3:
  - Added MII-Lite documentation

Changes in v4:
  - Added missing Fixes headers

Changes in v5:
  - Removed unused PHY register bits definition

Changes in v6:
  - Reworded the cover letter to explain why this series should be applied
   at once and routed through "net", not "net-next".

Changes in v7:
  - Reworded the cover letter again and routed to net-next on behalf of the
   maintainers. 

Kamil Horák - 2N (4):
  net: phy: MII-Lite PHY interface mode
  dt-bindings: ethernet-phy: add MII-Lite phy interface type
  net: phy: bcm5481x: MII-Lite activation
  net: phy: bcm54811: PHY initialization

 .../bindings/net/ethernet-controller.yaml     |  1 +
 Documentation/networking/phy.rst              |  7 ++++
 drivers/net/phy/broadcom.c                    | 39 ++++++++++++++++---
 drivers/net/phy/phy-core.c                    |  1 +
 drivers/net/phy/phy_caps.c                    |  4 ++
 drivers/net/phy/phylink.c                     |  1 +
 include/linux/brcmphy.h                       |  6 +++
 include/linux/phy.h                           |  4 ++
 8 files changed, 58 insertions(+), 5 deletions(-)

-- 
2.39.5

[PATCH net-next v7 1/4] net: phy: MII-Lite PHY interface mode

[Kamil Horák - 2N]

Some Broadcom PHYs are capable to operate in simplified MII mode,
without TXER, RXER, CRS and COL signals as defined for the MII.
The MII-Lite mode can be used on most Ethernet controllers with full
MII interface by just leaving the input signals (RXER, CRS, COL)
inactive. The absence of COL signal makes half-duplex link modes
impossible but does not interfere with BroadR-Reach link modes on
Broadcom PHYs, because they are all full-duplex only.

Add MII-Lite interface mode, especially for Broadcom two-wire PHYs.

Signed-off-by: Kamil Horák - 2N <kamilh@axis.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 Documentation/networking/phy.rst | 7 +++++++
 drivers/net/phy/phy-core.c       | 1 +
 drivers/net/phy/phy_caps.c       | 4 ++++
 drivers/net/phy/phylink.c        | 1 +
 include/linux/phy.h              | 4 ++++
 5 files changed, 17 insertions(+)

diff --git a/Documentation/networking/phy.rst b/Documentation/networking/phy.rst
index f64641417c54..7f159043ad5a 100644
--- a/Documentation/networking/phy.rst
+++ b/Documentation/networking/phy.rst
@@ -333,6 +333,13 @@ Some of the interface modes are described below:
     SerDes lane, each port having speeds of 2.5G / 1G / 100M / 10M achieved
     through symbol replication. The PCS expects the standard USXGMII code word.
 
+``PHY_INTERFACE_MODE_MIILITE``
+    Non-standard, simplified MII mode, without TXER, RXER, CRS and COL signals
+    as defined for the MII. The absence of COL signal makes half-duplex link
+    modes impossible but does not interfere with BroadR-Reach link modes on
+    Broadcom (and other two-wire Ethernet) PHYs, because they are full-duplex
+    only.
+
 Pause frames / flow control
 ===========================
 
diff --git a/drivers/net/phy/phy-core.c b/drivers/net/phy/phy-core.c
index c480bb40fa73..605ca20ae192 100644
--- a/drivers/net/phy/phy-core.c
+++ b/drivers/net/phy/phy-core.c
@@ -115,6 +115,7 @@ int phy_interface_num_ports(phy_interface_t interface)
 		return 0;
 	case PHY_INTERFACE_MODE_INTERNAL:
 	case PHY_INTERFACE_MODE_MII:
+	case PHY_INTERFACE_MODE_MIILITE:
 	case PHY_INTERFACE_MODE_GMII:
 	case PHY_INTERFACE_MODE_TBI:
 	case PHY_INTERFACE_MODE_REVMII:
diff --git a/drivers/net/phy/phy_caps.c b/drivers/net/phy/phy_caps.c
index d11ce1c7e712..2cc9ee97e867 100644
--- a/drivers/net/phy/phy_caps.c
+++ b/drivers/net/phy/phy_caps.c
@@ -316,6 +316,10 @@ unsigned long phy_caps_from_interface(phy_interface_t interface)
 		link_caps |= BIT(LINK_CAPA_100HD) | BIT(LINK_CAPA_100FD);
 		break;
 
+	case PHY_INTERFACE_MODE_MIILITE:
+		link_caps |= BIT(LINK_CAPA_10FD) | BIT(LINK_CAPA_100FD);
+		break;
+
 	case PHY_INTERFACE_MODE_TBI:
 	case PHY_INTERFACE_MODE_MOCA:
 	case PHY_INTERFACE_MODE_RTBI:
diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index f5473510b762..c7f867b361dd 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -237,6 +237,7 @@ static int phylink_interface_max_speed(phy_interface_t interface)
 	case PHY_INTERFACE_MODE_SMII:
 	case PHY_INTERFACE_MODE_REVMII:
 	case PHY_INTERFACE_MODE_MII:
+	case PHY_INTERFACE_MODE_MIILITE:
 		return SPEED_100;
 
 	case PHY_INTERFACE_MODE_TBI:
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 74c1bcf64b3c..43786bb8f804 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -106,6 +106,7 @@ extern const int phy_basic_ports_array[3];
  * @PHY_INTERFACE_MODE_50GBASER: 50GBase-R - with Clause 134 FEC
  * @PHY_INTERFACE_MODE_LAUI: 50 Gigabit Attachment Unit Interface
  * @PHY_INTERFACE_MODE_100GBASEP: 100GBase-P - with Clause 134 FEC
+ * @PHY_INTERFACE_MODE_MIILITE: MII-Lite - MII without RXER TXER CRS COL
  * @PHY_INTERFACE_MODE_MAX: Book keeping
  *
  * Describes the interface between the MAC and PHY.
@@ -150,6 +151,7 @@ typedef enum {
 	PHY_INTERFACE_MODE_50GBASER,
 	PHY_INTERFACE_MODE_LAUI,
 	PHY_INTERFACE_MODE_100GBASEP,
+	PHY_INTERFACE_MODE_MIILITE,
 	PHY_INTERFACE_MODE_MAX,
 } phy_interface_t;
 
@@ -272,6 +274,8 @@ static inline const char *phy_modes(phy_interface_t interface)
 		return "laui";
 	case PHY_INTERFACE_MODE_100GBASEP:
 		return "100gbase-p";
+	case PHY_INTERFACE_MODE_MIILITE:
+		return "mii-lite";
 	default:
 		return "unknown";
 	}
-- 
2.39.5

Re: [PATCH net-next v7 1/4] net: phy: MII-Lite PHY interface mode

[Russell King (Oracle)]

On Tue, Jul 08, 2025 at 11:01:37AM +0200, Kamil Horák - 2N wrote:
> Some Broadcom PHYs are capable to operate in simplified MII mode,
> without TXER, RXER, CRS and COL signals as defined for the MII.
> The MII-Lite mode can be used on most Ethernet controllers with full
> MII interface by just leaving the input signals (RXER, CRS, COL)
> inactive. The absence of COL signal makes half-duplex link modes
> impossible but does not interfere with BroadR-Reach link modes on
> Broadcom PHYs, because they are all full-duplex only.
> 
> Add MII-Lite interface mode, especially for Broadcom two-wire PHYs.
> 
> Signed-off-by: Kamil Horák - 2N <kamilh@axis.com>
> Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
> Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>

Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

Thanks!

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!

[PATCH net-next v7 2/4] dt-bindings: ethernet-phy: add MII-Lite phy interface type

[Kamil Horák - 2N]

Some Broadcom PHYs are capable to operate in simplified MII mode,
without TXER, RXER, CRS and COL signals as defined for the MII.
The MII-Lite mode can be used on most Ethernet controllers with full
MII interface by just leaving the input signals (RXER, CRS, COL)
inactive. The absence of COL signal makes half-duplex link modes
impossible but does not interfere with BroadR-Reach link modes on
Broadcom PHYs, because they are all full-duplex only.

Add new interface type "mii-lite" to phy-connection-type enum.

Signed-off-by: Kamil Horák - 2N <kamilh@axis.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 Documentation/devicetree/bindings/net/ethernet-controller.yaml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/net/ethernet-controller.yaml b/Documentation/devicetree/bindings/net/ethernet-controller.yaml
index 7cbf11bbe99c..66b1cfbbfe22 100644
--- a/Documentation/devicetree/bindings/net/ethernet-controller.yaml
+++ b/Documentation/devicetree/bindings/net/ethernet-controller.yaml
@@ -39,6 +39,7 @@ properties:
       # MAC.
       - internal
       - mii
+      - mii-lite
       - gmii
       - sgmii
       - psgmii
-- 
2.39.5

Re: [PATCH net-next v7 2/4] dt-bindings: ethernet-phy: add MII-Lite phy interface type

[Rob Herring (Arm)]

On Tue, 08 Jul 2025 11:01:38 +0200, Kamil Horák - 2N wrote:
> Some Broadcom PHYs are capable to operate in simplified MII mode,
> without TXER, RXER, CRS and COL signals as defined for the MII.
> The MII-Lite mode can be used on most Ethernet controllers with full
> MII interface by just leaving the input signals (RXER, CRS, COL)
> inactive. The absence of COL signal makes half-duplex link modes
> impossible but does not interfere with BroadR-Reach link modes on
> Broadcom PHYs, because they are all full-duplex only.
> 
> Add new interface type "mii-lite" to phy-connection-type enum.
> 
> Signed-off-by: Kamil Horák - 2N <kamilh@axis.com>
> Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
> Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
> ---
>  Documentation/devicetree/bindings/net/ethernet-controller.yaml | 1 +
>  1 file changed, 1 insertion(+)
> 

Acked-by: Rob Herring (Arm) <robh@kernel.org>

[PATCH net-next v7 3/4] net: phy: bcm5481x: MII-Lite activation

[Kamil Horák - 2N]

Broadcom PHYs featuring the BroadR-Reach two-wire link mode are usually
capable to operate in simplified MII mode, without TXER, RXER, CRS and
COL signals as defined for the MII. The absence of COL signal makes
half-duplex link modes impossible, however, the BroadR-Reach modes are
all full-duplex only.
Depending on the IC encapsulation, there exist MII-Lite-only PHYs such
as bcm54811 in MLP. The PHY itself is hardware-strapped to select among
multiple RGMII and MII-Lite modes, but the MII-Lite mode must be also
activated by software.

Add MII-Lite activation for bcm5481x PHYs.

Signed-off-by: Kamil Horák - 2N <kamilh@axis.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 drivers/net/phy/broadcom.c | 14 +++++++++++++-
 include/linux/brcmphy.h    |  6 ++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/broadcom.c b/drivers/net/phy/broadcom.c
index 9b1de54fd483..8547983bd72f 100644
--- a/drivers/net/phy/broadcom.c
+++ b/drivers/net/phy/broadcom.c
@@ -407,7 +407,7 @@ static int bcm5481x_set_brrmode(struct phy_device *phydev, bool on)
 static int bcm54811_config_init(struct phy_device *phydev)
 {
 	struct bcm54xx_phy_priv *priv = phydev->priv;
-	int err, reg;
+	int err, reg, exp_sync_ethernet;
 
 	/* Enable CLK125 MUX on LED4 if ref clock is enabled. */
 	if (!(phydev->dev_flags & PHY_BRCM_RX_REFCLK_UNUSED)) {
@@ -424,6 +424,18 @@ static int bcm54811_config_init(struct phy_device *phydev)
 	if (priv->brr_mode)
 		phydev->autoneg = 0;
 
+	/* Enable MII Lite (No TXER, RXER, CRS, COL) if configured */
+	if (phydev->interface == PHY_INTERFACE_MODE_MIILITE)
+		exp_sync_ethernet = BCM_EXP_SYNC_ETHERNET_MII_LITE;
+	else
+		exp_sync_ethernet = 0;
+
+	err = bcm_phy_modify_exp(phydev, BCM_EXP_SYNC_ETHERNET,
+				 BCM_EXP_SYNC_ETHERNET_MII_LITE,
+				 exp_sync_ethernet);
+	if (err < 0)
+		return err;
+
 	return bcm5481x_set_brrmode(phydev, priv->brr_mode);
 }
 
diff --git a/include/linux/brcmphy.h b/include/linux/brcmphy.h
index 028b3e00378e..15c35655f482 100644
--- a/include/linux/brcmphy.h
+++ b/include/linux/brcmphy.h
@@ -182,6 +182,12 @@
 #define BCM_LED_MULTICOLOR_ACT		0x9
 #define BCM_LED_MULTICOLOR_PROGRAM	0xa
 
+/*
+ * Broadcom Synchronous Ethernet Controls (expansion register 0x0E)
+ */
+#define BCM_EXP_SYNC_ETHERNET		(MII_BCM54XX_EXP_SEL_ER + 0x0E)
+#define BCM_EXP_SYNC_ETHERNET_MII_LITE	BIT(11)
+
 /*
  * BCM5482: Shadow registers
  * Shadow values go into bits [14:10] of register 0x1c to select a shadow
-- 
2.39.5

Re: [PATCH net-next v7 3/4] net: phy: bcm5481x: MII-Lite activation

[Russell King (Oracle)]

On Tue, Jul 08, 2025 at 11:01:39AM +0200, Kamil Horák - 2N wrote:
> Broadcom PHYs featuring the BroadR-Reach two-wire link mode are usually
> capable to operate in simplified MII mode, without TXER, RXER, CRS and
> COL signals as defined for the MII. The absence of COL signal makes
> half-duplex link modes impossible, however, the BroadR-Reach modes are
> all full-duplex only.
> Depending on the IC encapsulation, there exist MII-Lite-only PHYs such
> as bcm54811 in MLP. The PHY itself is hardware-strapped to select among
> multiple RGMII and MII-Lite modes, but the MII-Lite mode must be also
> activated by software.
> 
> Add MII-Lite activation for bcm5481x PHYs.
> 
> Signed-off-by: Kamil Horák - 2N <kamilh@axis.com>
> Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>

Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

Thanks!

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!

[PATCH net-next v7 4/4] net: phy: bcm54811: PHY initialization

[Kamil Horák - 2N]

Reset the bit 12 in PHY's LRE Control register upon initialization.
According to the datasheet, this bit must be written to zero after
every device reset.

Signed-off-by: Kamil Horák - 2N <kamilh@axis.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 drivers/net/phy/broadcom.c | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/drivers/net/phy/broadcom.c b/drivers/net/phy/broadcom.c
index 8547983bd72f..a60e58ef90c4 100644
--- a/drivers/net/phy/broadcom.c
+++ b/drivers/net/phy/broadcom.c
@@ -667,7 +667,7 @@ static int bcm5481x_read_abilities(struct phy_device *phydev)
 {
 	struct device_node *np = phydev->mdio.dev.of_node;
 	struct bcm54xx_phy_priv *priv = phydev->priv;
-	int i, val, err;
+	int i, val, err, aneg;
 
 	for (i = 0; i < ARRAY_SIZE(bcm54811_linkmodes); i++)
 		linkmode_clear_bit(bcm54811_linkmodes[i], phydev->supported);
@@ -688,9 +688,19 @@ static int bcm5481x_read_abilities(struct phy_device *phydev)
 		if (val < 0)
 			return val;
 
+		/* BCM54811 is not capable of LDS but the corresponding bit
+		 * in LRESR is set to 1 and marked "Ignore" in the datasheet.
+		 * So we must read the bcm54811 as unable to auto-negotiate
+		 * in BroadR-Reach mode.
+		 */
+		if (BRCM_PHY_MODEL(phydev) == PHY_ID_BCM54811)
+			aneg = 0;
+		else
+			aneg = val & LRESR_LDSABILITY;
+
 		linkmode_mod_bit(ETHTOOL_LINK_MODE_Autoneg_BIT,
 				 phydev->supported,
-				 val & LRESR_LDSABILITY);
+				 aneg);
 		linkmode_mod_bit(ETHTOOL_LINK_MODE_100baseT1_Full_BIT,
 				 phydev->supported,
 				 val & LRESR_100_1PAIR);
@@ -747,8 +757,15 @@ static int bcm54811_config_aneg(struct phy_device *phydev)
 
 	/* Aneg firstly. */
 	if (priv->brr_mode) {
-		/* BCM54811 is only capable of autonegotiation in IEEE mode */
-		phydev->autoneg = 0;
+		/* BCM54811 is only capable of autonegotiation in IEEE mode.
+		 * In BroadR-Reach mode, disable the Long Distance Signaling,
+		 * the BRR mode autoneg as supported in other Broadcom PHYs.
+		 * This bit is marked as "Reserved" and "Default 1, must be
+		 *  written to 0 after every device reset" in the datasheet.
+		 */
+		ret = phy_modify(phydev, MII_BCM54XX_LRECR, LRECR_LDSEN, 0);
+		if (ret < 0)
+			return ret;
 		ret = bcm_config_lre_aneg(phydev, false);
 	} else {
 		ret = genphy_config_aneg(phydev);
-- 
2.39.5

Re: [PATCH net-next v7 0/4] net: phy: bcm54811: PHY initialization

[patchwork-bot+netdevbpf]

Hello:

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

On Tue, 8 Jul 2025 11:01:36 +0200 you wrote:
> Proper bcm54811 PHY driver initialization for MII-Lite.
> 
> The bcm54811 PHY in MLP package must be setup for MII-Lite interface
> mode by software. Normally, the PHY to MAC interface is selected in
> hardware by setting the bootstrap pins of the PHY. However, MII and
> MII-Lite share the same hardware setup and must be distinguished by
> software, setting appropriate bit in a configuration register.
> The MII-Lite interface mode is non-standard one, defined by Broadcom
> for some of their PHYs. The MII-Lite lightness consist in omitting
> RXER, TXER, CRS and COL signals of the standard MII interface.
> Absence of COL them makes half-duplex links modes impossible but
> does not interfere with Broadcom's BroadR-Reach link modes, because
> they are full-duplex only.
> To do it in a clean way, MII-Lite must be introduced first, including
> its limitation to link modes (no half-duplex), because it is a
> prerequisite for the patch #3 of this series. The patch #4 does not
> depend on MII-Lite directly but both #3 and #4 are necessary for
> bcm54811 to work properly without additional configuration steps to be
> done - for example in the bootloader, before the kernel starts.
> 
> [...]

Here is the summary with links:
  - [net-next,v7,1/4] net: phy: MII-Lite PHY interface mode
    https://git.kernel.org/netdev/net-next/c/67c0170566b5
  - [net-next,v7,2/4] dt-bindings: ethernet-phy: add MII-Lite phy interface type
    https://git.kernel.org/netdev/net-next/c/fbe937473f3a
  - [net-next,v7,3/4] net: phy: bcm5481x: MII-Lite activation
    https://git.kernel.org/netdev/net-next/c/34bf222824f6
  - [net-next,v7,4/4] net: phy: bcm54811: PHY initialization
    https://git.kernel.org/netdev/net-next/c/3117a11fff5a

You are awesome, thank you!
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