[PATCH v2 0/2] net: phy: adin: enable configuration of the LP Termination Register

[PATCH v2 0/2] net: phy: adin: enable configuration of the LP Termination Register

[Osose Itua]

Changes since v1:
- rework phy_read_mmd() error handling

Osose Itua (2):
  net: phy: adin: enable configuration of the LP Termination Register
  dt-bindings: net: adi,adin: document LP Termination property

 .../devicetree/bindings/net/adi,adin.yaml     |  6 ++++
 drivers/net/phy/adin.c                        | 34 +++++++++++++++++++
 2 files changed, 40 insertions(+)

[PATCH v2 1/2] net: phy: adin: enable configuration of the LP Termination Register

[Osose Itua]

The ADIN1200/ADIN1300 provide a control bit that selects between normal
receive termination and the lowest common mode impedance for 100BASE-TX
operation. This behavior is controlled through the Low Power Termination
register (B_100_ZPTM_EN_DIMRX).

Bit 0 of this register enables normal termination when set (this is the
default), and selects the lowest common mode impedance when cleared.

Signed-off-by: Osose Itua <osose.itua@savoirfairelinux.com>
---
 drivers/net/phy/adin.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/drivers/net/phy/adin.c b/drivers/net/phy/adin.c
index 7fa713ca8d45..e8b778cb191d 100644
--- a/drivers/net/phy/adin.c
+++ b/drivers/net/phy/adin.c
@@ -4,6 +4,7 @@
  *
  * Copyright 2019 Analog Devices Inc.
  */
+#include <cerrno>
 #include <linux/kernel.h>
 #include <linux/bitfield.h>
 #include <linux/delay.h>
@@ -89,6 +90,9 @@
 #define ADIN1300_CLOCK_STOP_REG			0x9400
 #define ADIN1300_LPI_WAKE_ERR_CNT_REG		0xa000
 
+#define ADIN1300_B_100_ZPTM_DIMRX		0xB685
+#define ADIN1300_B_100_ZPTM_EN_DIMRX		BIT(0)
+
 #define ADIN1300_CDIAG_RUN			0xba1b
 #define   ADIN1300_CDIAG_RUN_EN			BIT(0)
 
@@ -522,6 +526,32 @@ static int adin_config_clk_out(struct phy_device *phydev)
 			      ADIN1300_GE_CLK_CFG_MASK, sel);
 }
 
+static int adin_config_zptm100(struct phy_device *phydev)
+{
+	struct device *dev = &phydev->mdio.dev;
+	int reg;
+	int rc;
+
+	if (!(device_property_read_bool(dev, "adi,low-cmode-impedance")))
+		return 0;
+
+	/* set to 0 to configure for lowest common-mode impedance */
+	rc = phy_write_mmd(phydev, MDIO_MMD_VEND1, ADIN1300_B_100_ZPTM_DIMRX, 0x0);
+	if (rc < 0)
+		return rc;
+
+	reg = phy_read_mmd(phydev, MDIO_MMD_VEND1, ADIN1300_B_100_ZPTM_DIMRX);
+	if (reg < 0)
+		return reg;
+
+	if (!(reg & ADIN1300_B_100_ZPTM_EN_DIMRX)) {
+		phydev_err(phydev, "Failed to set lowest common-mode impedance.\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static int adin_config_init(struct phy_device *phydev)
 {
 	int rc;
@@ -548,6 +578,10 @@ static int adin_config_init(struct phy_device *phydev)
 	if (rc < 0)
 		return rc;
 
+	rc = adin_config_zptm100(phydev);
+	if (rc < 0)
+		return rc;
+
 	phydev_dbg(phydev, "PHY is using mode '%s'\n",
 		   phy_modes(phydev->interface));
 

[PATCH v2 2/2] dt-bindings: net: adi,adin: document LP Termination property

[Osose Itua]

Add "adi,low-cmode-impedance" boolean property which, when present,
configures the PHY for the lowest common-mode impedance on the receive
pair for 100BASE-TX operation.

Signed-off-by: Osose Itua <osose.itua@savoirfairelinux.com>
---
 Documentation/devicetree/bindings/net/adi,adin.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/adi,adin.yaml b/Documentation/devicetree/bindings/net/adi,adin.yaml
index c425a9f1886d..d3c8c5cc4bb1 100644
--- a/Documentation/devicetree/bindings/net/adi,adin.yaml
+++ b/Documentation/devicetree/bindings/net/adi,adin.yaml
@@ -52,6 +52,12 @@ properties:
     description: Enable 25MHz reference clock output on CLK25_REF pin.
     type: boolean
 
+  adi,low-cmode-impedance:
+    description: |
+      Ability to configure for the lowest common-mode impedance on the
+      receive pair for 100BASE-TX.
+    type: boolean
+
 unevaluatedProperties: false
 
 examples:

Re: [PATCH v2 1/2] net: phy: adin: enable configuration of the LP Termination Register

[Subbaraya Sundeep]

Hi,

On 2025-12-23 at 03:51:04, Osose Itua (osose.itua@savoirfairelinux.com) wrote:
> The ADIN1200/ADIN1300 provide a control bit that selects between normal
> receive termination and the lowest common mode impedance for 100BASE-TX
> operation. This behavior is controlled through the Low Power Termination
> register (B_100_ZPTM_EN_DIMRX).
> 
> Bit 0 of this register enables normal termination when set (this is the
> default), and selects the lowest common mode impedance when cleared.
> 
> Signed-off-by: Osose Itua <osose.itua@savoirfairelinux.com>
> ---
>  drivers/net/phy/adin.c | 34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/drivers/net/phy/adin.c b/drivers/net/phy/adin.c
> index 7fa713ca8d45..e8b778cb191d 100644
> --- a/drivers/net/phy/adin.c
> +++ b/drivers/net/phy/adin.c
> @@ -4,6 +4,7 @@
>   *
>   * Copyright 2019 Analog Devices Inc.
>   */
> +#include <cerrno>
>  #include <linux/kernel.h>
>  #include <linux/bitfield.h>
>  #include <linux/delay.h>
> @@ -89,6 +90,9 @@
>  #define ADIN1300_CLOCK_STOP_REG			0x9400
>  #define ADIN1300_LPI_WAKE_ERR_CNT_REG		0xa000
>  
> +#define ADIN1300_B_100_ZPTM_DIMRX		0xB685
> +#define ADIN1300_B_100_ZPTM_EN_DIMRX		BIT(0)
> +
>  #define ADIN1300_CDIAG_RUN			0xba1b
>  #define   ADIN1300_CDIAG_RUN_EN			BIT(0)
>  
> @@ -522,6 +526,32 @@ static int adin_config_clk_out(struct phy_device *phydev)
>  			      ADIN1300_GE_CLK_CFG_MASK, sel);
>  }
>  
> +static int adin_config_zptm100(struct phy_device *phydev)
> +{
> +	struct device *dev = &phydev->mdio.dev;
> +	int reg;
> +	int rc;
> +
> +	if (!(device_property_read_bool(dev, "adi,low-cmode-impedance")))
> +		return 0;
> +
> +	/* set to 0 to configure for lowest common-mode impedance */
> +	rc = phy_write_mmd(phydev, MDIO_MMD_VEND1, ADIN1300_B_100_ZPTM_DIMRX, 0x0);

This clears full register instead of just bit 0. Is that intended?

> +	if (rc < 0)
> +		return rc;
> +
> +	reg = phy_read_mmd(phydev, MDIO_MMD_VEND1, ADIN1300_B_100_ZPTM_DIMRX);
> +	if (reg < 0)
> +		return reg;
> +
> +	if (!(reg & ADIN1300_B_100_ZPTM_EN_DIMRX)) {

From commit description, check should be if (reg & ADIN1300_B_100_ZPTM_EN_DIMRX)
AI review also caught this:
https://netdev-ai.bots.linux.dev/ai-review.html?id=05b38bb2-1244-46fc-a4d9-311ca8c825ee#patch-0

Fix the build errors reported at:
https://patchwork.kernel.org/project/netdevbpf/patch/20251222222210.3651577-2-osose.itua@savoirfairelinux.com/

Also net-next is closed till Jan 2. Please post v3 after that.

Thanks,
Sundeep
> +		phydev_err(phydev, "Failed to set lowest common-mode impedance.\n");
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
>  static int adin_config_init(struct phy_device *phydev)
>  {
>  	int rc;
> @@ -548,6 +578,10 @@ static int adin_config_init(struct phy_device *phydev)
>  	if (rc < 0)
>  		return rc;
>  
> +	rc = adin_config_zptm100(phydev);
> +	if (rc < 0)
> +		return rc;
> +
>  	phydev_dbg(phydev, "PHY is using mode '%s'\n",
>  		   phy_modes(phydev->interface));
>  

Re: [PATCH v2 1/2] net: phy: adin: enable configuration of the LP Termination Register

[Vadim Fedorenko]

On 22/12/2025 22:21, Osose Itua wrote:
> The ADIN1200/ADIN1300 provide a control bit that selects between normal
> receive termination and the lowest common mode impedance for 100BASE-TX
> operation. This behavior is controlled through the Low Power Termination
> register (B_100_ZPTM_EN_DIMRX).
> 
> Bit 0 of this register enables normal termination when set (this is the
> default), and selects the lowest common mode impedance when cleared.
> 
> Signed-off-by: Osose Itua <osose.itua@savoirfairelinux.com>
> ---
>   drivers/net/phy/adin.c | 34 ++++++++++++++++++++++++++++++++++
>   1 file changed, 34 insertions(+)
> 
> diff --git a/drivers/net/phy/adin.c b/drivers/net/phy/adin.c
> index 7fa713ca8d45..e8b778cb191d 100644
> --- a/drivers/net/phy/adin.c
> +++ b/drivers/net/phy/adin.c
> @@ -4,6 +4,7 @@
>    *
>    * Copyright 2019 Analog Devices Inc.
>    */
> +#include <cerrno>

This kind of include is not used in kernel.
You don't need to include anything in this file to have EINVAL defined.

>   #include <linux/kernel.h>
>   #include <linux/bitfield.h>
>   #include <linux/delay.h>
> @@ -89,6 +90,9 @@

Re: [PATCH v2 2/2] dt-bindings: net: adi,adin: document LP Termination property

[Andrew Lunn]

On Mon, Dec 22, 2025 at 05:21:05PM -0500, Osose Itua wrote:
> Add "adi,low-cmode-impedance" boolean property which, when present,
> configures the PHY for the lowest common-mode impedance on the receive
> pair for 100BASE-TX operation.

FYI: The DT Maintainers prefer that binding patches come first in a
patchset.

> diff --git a/Documentation/devicetree/bindings/net/adi,adin.yaml b/Documentation/devicetree/bindings/net/adi,adin.yaml
> index c425a9f1886d..d3c8c5cc4bb1 100644
> --- a/Documentation/devicetree/bindings/net/adi,adin.yaml
> +++ b/Documentation/devicetree/bindings/net/adi,adin.yaml
> @@ -52,6 +52,12 @@ properties:
>      description: Enable 25MHz reference clock output on CLK25_REF pin.
>      type: boolean
>  
> +  adi,low-cmode-impedance:
> +    description: |
> +      Ability to configure for the lowest common-mode impedance on the
> +      receive pair for 100BASE-TX.
> +    type: boolean

You should document that happens if the property is not present. Is
the hardware left alone, so the bootloader might of set it to
something other than reset defaults? Is it forced to the highest
common-mode impedance?

Also, is this an on/off setting? Or are there a range of impedance
values which can be set in the hardware? If it is a range, we might
want to be forward thinking and allow a value in ohms.

	Andrew

Re: [PATCH v2 1/2] net: phy: adin: enable configuration of the LP Termination Register

[Andrew Lunn]

> +static int adin_config_zptm100(struct phy_device *phydev)
> +{
> +	struct device *dev = &phydev->mdio.dev;
> +	int reg;
> +	int rc;
> +
> +	if (!(device_property_read_bool(dev, "adi,low-cmode-impedance")))
> +		return 0;
> +
> +	/* set to 0 to configure for lowest common-mode impedance */
> +	rc = phy_write_mmd(phydev, MDIO_MMD_VEND1, ADIN1300_B_100_ZPTM_DIMRX, 0x0);
> +	if (rc < 0)
> +		return rc;
> +
> +	reg = phy_read_mmd(phydev, MDIO_MMD_VEND1, ADIN1300_B_100_ZPTM_DIMRX);
> +	if (reg < 0)
> +		return reg;
> +
> +	if (!(reg & ADIN1300_B_100_ZPTM_EN_DIMRX)) {
> +		phydev_err(phydev, "Failed to set lowest common-mode impedance.\n");
> +		return -EINVAL;
> +	}

Under what condition do you think this could happen? Do you think
there are variants of the hardware which do not have this register?

	Andrew

Re: [PATCH v2 1/2] net: phy: adin: enable configuration of the LP Termination Register

[kernel test robot]

Hi Osose,

kernel test robot noticed the following build errors:

[auto build test ERROR on net/main]
[also build test ERROR on net-next/main linus/master horms-ipvs/master v6.19-rc2 next-20251219]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Osose-Itua/net-phy-adin-enable-configuration-of-the-LP-Termination-Register/20251223-064926
base:   net/main
patch link:    https://lore.kernel.org/r/20251222222210.3651577-2-osose.itua%40savoirfairelinux.com
patch subject: [PATCH v2 1/2] net: phy: adin: enable configuration of the LP Termination Register
config: parisc-randconfig-001-20251223 (https://download.01.org/0day-ci/archive/20251223/202512232150.85cDPKrJ-lkp@intel.com/config)
compiler: hppa-linux-gcc (GCC) 8.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251223/202512232150.85cDPKrJ-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202512232150.85cDPKrJ-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/net/phy/adin.c:7:10: fatal error: cerrno: No such file or directory
    #include <cerrno>
             ^~~~~~~~
   compilation terminated.


vim +7 drivers/net/phy/adin.c

   > 7	#include <cerrno>
     8	#include <linux/kernel.h>
     9	#include <linux/bitfield.h>
    10	#include <linux/delay.h>
    11	#include <linux/errno.h>
    12	#include <linux/ethtool_netlink.h>
    13	#include <linux/init.h>
    14	#include <linux/module.h>
    15	#include <linux/mii.h>
    16	#include <linux/phy.h>
    17	#include <linux/property.h>
    18	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v2 1/2] net: phy: adin: enable configuration of the LP Termination Register

[kernel test robot]

Hi Osose,

kernel test robot noticed the following build errors:

[auto build test ERROR on net/main]
[also build test ERROR on net-next/main linus/master horms-ipvs/master v6.19-rc2 next-20251219]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Osose-Itua/net-phy-adin-enable-configuration-of-the-LP-Termination-Register/20251223-064926
base:   net/main
patch link:    https://lore.kernel.org/r/20251222222210.3651577-2-osose.itua%40savoirfairelinux.com
patch subject: [PATCH v2 1/2] net: phy: adin: enable configuration of the LP Termination Register
config: hexagon-randconfig-002-20251223 (https://download.01.org/0day-ci/archive/20251223/202512232136.7GHkdaw8-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 4ef602d446057dabf5f61fb221669ecbeda49279)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251223/202512232136.7GHkdaw8-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202512232136.7GHkdaw8-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/net/phy/adin.c:7:10: fatal error: 'cerrno' file not found
       7 | #include <cerrno>
         |          ^~~~~~~~
   1 error generated.


vim +/cerrno +7 drivers/net/phy/adin.c

   > 7	#include <cerrno>
     8	#include <linux/kernel.h>
     9	#include <linux/bitfield.h>
    10	#include <linux/delay.h>
    11	#include <linux/errno.h>
    12	#include <linux/ethtool_netlink.h>
    13	#include <linux/init.h>
    14	#include <linux/module.h>
    15	#include <linux/mii.h>
    16	#include <linux/phy.h>
    17	#include <linux/property.h>
    18	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v2 2/2] dt-bindings: net: adi,adin: document LP Termination property

[Krzysztof Kozlowski]

On Mon, Dec 22, 2025 at 05:21:05PM -0500, Osose Itua wrote:
> Add "adi,low-cmode-impedance" boolean property which, when present,
> configures the PHY for the lowest common-mode impedance on the receive
> pair for 100BASE-TX operation.
> 
> Signed-off-by: Osose Itua <osose.itua@savoirfairelinux.com>
> ---
>  Documentation/devicetree/bindings/net/adi,adin.yaml | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/net/adi,adin.yaml b/Documentation/devicetree/bindings/net/adi,adin.yaml
> index c425a9f1886d..d3c8c5cc4bb1 100644
> --- a/Documentation/devicetree/bindings/net/adi,adin.yaml
> +++ b/Documentation/devicetree/bindings/net/adi,adin.yaml
> @@ -52,6 +52,12 @@ properties:
>      description: Enable 25MHz reference clock output on CLK25_REF pin.
>      type: boolean
>  
> +  adi,low-cmode-impedance:
> +    description: |
> +      Ability to configure for the lowest common-mode impedance on the

Either this is ability or you configure the PHY, as written in commit
msg. The latter suggests that's a SW property, not hardware, thus not
for bindings.

If the first, then why it is not implied by PHY itself - the compatible
(which is missing which makes this binding not selectable).

Best regards,
Krzysztof