[PATCH net-next v4 0/2] dsa: mxl-gsw1xx: Support R(G)MII slew rate configuration

[PATCH net-next v4 0/2] dsa: mxl-gsw1xx: Support R(G)MII slew rate configuration

[A. Sverdlin]

From: Alexander Sverdlin <alexander.sverdlin@siemens.com>

Maxlinear GSW1xx switches offer slew rate configuration bits for R(G)MII
interface. The default state of the configuration bits is "normal", while
"slow" can be used to reduce the radiated emissions. Add the support for
the latter option into the driver as well as the new DT bindings.

Changelog:
v4:
- separate properties for TXD and TXC pads
v3:
- use [pinctrl] standard "slew-rate" property as suggested by Rob
  https://lore.kernel.org/all/20251219204324.GA3881969-robh@kernel.org/
- better sorted struct gswip_hw_info initialisers as suggested by Daniel
- https://lore.kernel.org/all/20260105175320.2141753-1-alexander.sverdlin@siemens.com/
v2:
- do not hijack gsw1xx_phylink_mac_select_pcs() for configuring the port,
  introduce struct gswip_hw_info::port_setup callback
- actively configure "normal" slew rate (if the new DT property is missing)
- properly use regmap_set_bits() (v1 had reg and value mixed up)
- https://lore.kernel.org/all/20251216121705.65156-1-alexander.sverdlin@siemens.com/
v1:
- https://lore.kernel.org/all/20251212204557.2082890-1-alexander.sverdlin@siemens.com/

Alexander Sverdlin (2):
  dt-bindings: net: dsa: lantiq,gswip: add MaxLinear R(G)MII slew rate
  net: dsa: mxl-gsw1xx: Support R(G)MII slew rate configuration

 .../bindings/net/dsa/lantiq,gswip.yaml        | 14 +++++++
 drivers/net/dsa/lantiq/lantiq_gswip.h         |  1 +
 drivers/net/dsa/lantiq/lantiq_gswip_common.c  |  6 +++
 drivers/net/dsa/lantiq/mxl-gsw1xx.c           | 40 +++++++++++++++++++
 drivers/net/dsa/lantiq/mxl-gsw1xx.h           |  2 +
 5 files changed, 63 insertions(+)

-- 
2.52.0

[PATCH net-next v4 1/2] dt-bindings: net: dsa: lantiq,gswip: add MaxLinear R(G)MII slew rate

[A. Sverdlin]

From: Alexander Sverdlin <alexander.sverdlin@siemens.com>

Add new maxlinear,slew-rate-txc and maxlinear,slew-rate-txd uint32
properties. The properties are only applicable for ports in R(G)MII mode
and allow for slew rate reduction in comparison to "normal" default
configuration with the purpose to reduce radiated emissions.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
---
Changelog:
v4:
- separate properties for TXD and TXC pads ("maxlinear," prefix re-appears)
v3:
- use [pinctrl] standard "slew-rate" property as suggested by Rob
  https://lore.kernel.org/all/20251219204324.GA3881969-robh@kernel.org/
v2:
- unchanged

 .../devicetree/bindings/net/dsa/lantiq,gswip.yaml  | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml b/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
index 205b683849a53..747106810cc17 100644
--- a/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
+++ b/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
@@ -106,6 +106,20 @@ patternProperties:
         unevaluatedProperties: false
 
         properties:
+          maxlinear,slew-rate-txc:
+            $ref: /schemas/types.yaml#/definitions/uint32
+            enum: [0, 1]
+            description: |
+              RMII/RGMII TX Clock Slew Rate:
+              0: "Normal"
+              1: "Slow"
+          maxlinear,slew-rate-txd:
+            $ref: /schemas/types.yaml#/definitions/uint32
+            enum: [0, 1]
+            description: |
+              RMII/RGMII TX Non-Clock PAD Slew Rate:
+              0: "Normal"
+              1: "Slow"
           maxlinear,rmii-refclk-out:
             type: boolean
             description:
-- 
2.52.0

Re: [PATCH net-next v4 1/2] dt-bindings: net: dsa: lantiq,gswip: add MaxLinear R(G)MII slew rate

[Rob Herring]

On Wed, Jan 07, 2026 at 10:00:16AM +0100, A. Sverdlin wrote:
> From: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> 
> Add new maxlinear,slew-rate-txc and maxlinear,slew-rate-txd uint32
> properties. The properties are only applicable for ports in R(G)MII mode
> and allow for slew rate reduction in comparison to "normal" default
> configuration with the purpose to reduce radiated emissions.
> 
> Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> ---
> Changelog:
> v4:
> - separate properties for TXD and TXC pads ("maxlinear," prefix re-appears)
> v3:
> - use [pinctrl] standard "slew-rate" property as suggested by Rob
>   https://lore.kernel.org/all/20251219204324.GA3881969-robh@kernel.org/
> v2:
> - unchanged
> 
>  .../devicetree/bindings/net/dsa/lantiq,gswip.yaml  | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml b/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
> index 205b683849a53..747106810cc17 100644
> --- a/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
> +++ b/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
> @@ -106,6 +106,20 @@ patternProperties:
>          unevaluatedProperties: false
>  
>          properties:
> +          maxlinear,slew-rate-txc:
> +            $ref: /schemas/types.yaml#/definitions/uint32
> +            enum: [0, 1]

default: 0

> +            description: |
> +              RMII/RGMII TX Clock Slew Rate:

blank line
> +              0: "Normal"
> +              1: "Slow"

Indent lists by 2 more spaces. Drop the quotes.

> +          maxlinear,slew-rate-txd:
> +            $ref: /schemas/types.yaml#/definitions/uint32
> +            enum: [0, 1]
> +            description: |
> +              RMII/RGMII TX Non-Clock PAD Slew Rate:
> +              0: "Normal"
> +              1: "Slow"
>            maxlinear,rmii-refclk-out:
>              type: boolean
>              description:
> -- 
> 2.52.0
> 

Re: [PATCH net-next v4 1/2] dt-bindings: net: dsa: lantiq,gswip: add MaxLinear R(G)MII slew rate

[Daniel Golle]

On Tue, Jan 13, 2026 at 10:41:28AM -0600, Rob Herring wrote:
> On Wed, Jan 07, 2026 at 10:00:16AM +0100, A. Sverdlin wrote:
> > From: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> > 
> > Add new maxlinear,slew-rate-txc and maxlinear,slew-rate-txd uint32
> > properties. The properties are only applicable for ports in R(G)MII mode
> > and allow for slew rate reduction in comparison to "normal" default
> > configuration with the purpose to reduce radiated emissions.
> > 
> > Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> > ---
> > Changelog:
> > v4:
> > - separate properties for TXD and TXC pads ("maxlinear," prefix re-appears)
> > v3:
> > - use [pinctrl] standard "slew-rate" property as suggested by Rob
> >   https://lore.kernel.org/all/20251219204324.GA3881969-robh@kernel.org/
> > v2:
> > - unchanged
> > 
> >  .../devicetree/bindings/net/dsa/lantiq,gswip.yaml  | 14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml b/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
> > index 205b683849a53..747106810cc17 100644
> > --- a/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
> > +++ b/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
> > @@ -106,6 +106,20 @@ patternProperties:
> >          unevaluatedProperties: false
> >  
> >          properties:
> > +          maxlinear,slew-rate-txc:
> > +            $ref: /schemas/types.yaml#/definitions/uint32
> > +            enum: [0, 1]
> 
> default: 0

Not really. The default is not to touch the register value which may
have already been setup by the bootloader.

> 
> > +            description: |
> > +              RMII/RGMII TX Clock Slew Rate:
> 
> blank line
> > +              0: "Normal"
> > +              1: "Slow"
> 
> Indent lists by 2 more spaces. Drop the quotes.
> 
> > +          maxlinear,slew-rate-txd:
> > +            $ref: /schemas/types.yaml#/definitions/uint32
> > +            enum: [0, 1]
> > +            description: |
> > +              RMII/RGMII TX Non-Clock PAD Slew Rate:
> > +              0: "Normal"
> > +              1: "Slow"
> >            maxlinear,rmii-refclk-out:
> >              type: boolean
> >              description:
> > -- 
> > 2.52.0
> > 

Re: [PATCH net-next v4 1/2] dt-bindings: net: dsa: lantiq,gswip: add MaxLinear R(G)MII slew rate

[Rob Herring]

On Tue, Jan 13, 2026 at 10:59 AM Daniel Golle <daniel@makrotopia.org> wrote:
>
> On Tue, Jan 13, 2026 at 10:41:28AM -0600, Rob Herring wrote:
> > On Wed, Jan 07, 2026 at 10:00:16AM +0100, A. Sverdlin wrote:
> > > From: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> > >
> > > Add new maxlinear,slew-rate-txc and maxlinear,slew-rate-txd uint32
> > > properties. The properties are only applicable for ports in R(G)MII mode
> > > and allow for slew rate reduction in comparison to "normal" default
> > > configuration with the purpose to reduce radiated emissions.
> > >
> > > Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> > > ---
> > > Changelog:
> > > v4:
> > > - separate properties for TXD and TXC pads ("maxlinear," prefix re-appears)
> > > v3:
> > > - use [pinctrl] standard "slew-rate" property as suggested by Rob
> > >   https://lore.kernel.org/all/20251219204324.GA3881969-robh@kernel.org/
> > > v2:
> > > - unchanged
> > >
> > >  .../devicetree/bindings/net/dsa/lantiq,gswip.yaml  | 14 ++++++++++++++
> > >  1 file changed, 14 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml b/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
> > > index 205b683849a53..747106810cc17 100644
> > > --- a/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
> > > +++ b/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
> > > @@ -106,6 +106,20 @@ patternProperties:
> > >          unevaluatedProperties: false
> > >
> > >          properties:
> > > +          maxlinear,slew-rate-txc:
> > > +            $ref: /schemas/types.yaml#/definitions/uint32
> > > +            enum: [0, 1]
> >
> > default: 0
>
> Not really. The default is not to touch the register value which may
> have already been setup by the bootloader.

Okay, please add that to the description.

Rob

[PATCH net-next v4 2/2] net: dsa: mxl-gsw1xx: Support R(G)MII slew rate configuration

[A. Sverdlin]

From: Alexander Sverdlin <alexander.sverdlin@siemens.com>

Support newly introduced maxlinear,slew-rate-txc and
maxlinear,slew-rate-txd device tree properties to configure R(G)MII
interface pins' slew rate. It might be used to reduce the radiated
emissions.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
---
Changelog:
v4:
- separate properties for TXD and TXC pads
v3:
- use [pinctrl] standard "slew-rate" property as suggested by Rob
  https://lore.kernel.org/all/20251219204324.GA3881969-robh@kernel.org/
- better sorted struct gswip_hw_info initialisers as suggested by Daniel
v2:
- do not hijack gsw1xx_phylink_mac_select_pcs() for configuring the port,
  introduce struct gswip_hw_info::port_setup callback
- actively configure "normal" slew rate (if the new DT property is missing)
- properly use regmap_set_bits() (v1 had reg and value mixed up)

 drivers/net/dsa/lantiq/lantiq_gswip.h        |  1 +
 drivers/net/dsa/lantiq/lantiq_gswip_common.c |  6 +++
 drivers/net/dsa/lantiq/mxl-gsw1xx.c          | 40 ++++++++++++++++++++
 drivers/net/dsa/lantiq/mxl-gsw1xx.h          |  2 +
 4 files changed, 49 insertions(+)

diff --git a/drivers/net/dsa/lantiq/lantiq_gswip.h b/drivers/net/dsa/lantiq/lantiq_gswip.h
index 2e0f2afbadbbc..8fc4c7cc5283a 100644
--- a/drivers/net/dsa/lantiq/lantiq_gswip.h
+++ b/drivers/net/dsa/lantiq/lantiq_gswip.h
@@ -263,6 +263,7 @@ struct gswip_hw_info {
 				 struct phylink_config *config);
 	struct phylink_pcs *(*mac_select_pcs)(struct phylink_config *config,
 					      phy_interface_t interface);
+	int (*port_setup)(struct dsa_switch *ds, int port);
 };
 
 struct gswip_gphy_fw {
diff --git a/drivers/net/dsa/lantiq/lantiq_gswip_common.c b/drivers/net/dsa/lantiq/lantiq_gswip_common.c
index e790f2ef75884..17a61e445f00f 100644
--- a/drivers/net/dsa/lantiq/lantiq_gswip_common.c
+++ b/drivers/net/dsa/lantiq/lantiq_gswip_common.c
@@ -425,6 +425,12 @@ static int gswip_port_setup(struct dsa_switch *ds, int port)
 	struct gswip_priv *priv = ds->priv;
 	int err;
 
+	if (priv->hw_info->port_setup) {
+		err = priv->hw_info->port_setup(ds, port);
+		if (err)
+			return err;
+	}
+
 	if (!dsa_is_cpu_port(ds, port)) {
 		err = gswip_add_single_port_br(priv, port, true);
 		if (err)
diff --git a/drivers/net/dsa/lantiq/mxl-gsw1xx.c b/drivers/net/dsa/lantiq/mxl-gsw1xx.c
index f8ff8a604bf53..6afc7539fefbe 100644
--- a/drivers/net/dsa/lantiq/mxl-gsw1xx.c
+++ b/drivers/net/dsa/lantiq/mxl-gsw1xx.c
@@ -559,6 +559,43 @@ static struct phylink_pcs *gsw1xx_phylink_mac_select_pcs(struct phylink_config *
 	}
 }
 
+static int gsw1xx_rmii_slew_rate(const struct device_node *np, struct gsw1xx_priv *priv,
+				 const char *prop, u16 mask)
+{
+	u32 rate;
+	int ret;
+
+	ret = of_property_read_u32(np, prop, &rate);
+	/* Optional property */
+	if (ret == -EINVAL)
+		return 0;
+	if (ret < 0 || rate > 1) {
+		dev_err(&priv->mdio_dev->dev, "Invalid %s value\n", prop);
+		return (ret < 0) ? ret : -EINVAL;
+	}
+
+	return regmap_update_bits(priv->shell, GSW1XX_SHELL_RGMII_SLEW_CFG, mask, mask * rate);
+}
+
+static int gsw1xx_port_setup(struct dsa_switch *ds, int port)
+{
+	struct dsa_port *dp = dsa_to_port(ds, port);
+	struct device_node *np = dp->dn;
+	struct gsw1xx_priv *gsw1xx_priv;
+	struct gswip_priv *gswip_priv;
+
+	if (dp->index != GSW1XX_MII_PORT)
+		return 0;
+
+	gswip_priv = ds->priv;
+	gsw1xx_priv = container_of(gswip_priv, struct gsw1xx_priv, gswip);
+
+	return gsw1xx_rmii_slew_rate(np, gsw1xx_priv,
+				     "maxlinear,slew-rate-txc", RGMII_SLEW_CFG_DRV_TXC) ?:
+	       gsw1xx_rmii_slew_rate(np, gsw1xx_priv,
+				     "maxlinear,slew-rate-txd", RGMII_SLEW_CFG_DRV_TXD);
+}
+
 static struct regmap *gsw1xx_regmap_init(struct gsw1xx_priv *priv,
 					 const char *name,
 					 unsigned int reg_base,
@@ -707,6 +744,7 @@ static const struct gswip_hw_info gsw12x_data = {
 	.mac_select_pcs		= gsw1xx_phylink_mac_select_pcs,
 	.phylink_get_caps	= &gsw1xx_phylink_get_caps,
 	.supports_2500m		= true,
+	.port_setup		= gsw1xx_port_setup,
 	.pce_microcode		= &gsw1xx_pce_microcode,
 	.pce_microcode_size	= ARRAY_SIZE(gsw1xx_pce_microcode),
 	.tag_protocol		= DSA_TAG_PROTO_MXL_GSW1XX,
@@ -720,6 +758,7 @@ static const struct gswip_hw_info gsw140_data = {
 	.mac_select_pcs		= gsw1xx_phylink_mac_select_pcs,
 	.phylink_get_caps	= &gsw1xx_phylink_get_caps,
 	.supports_2500m		= true,
+	.port_setup		= gsw1xx_port_setup,
 	.pce_microcode		= &gsw1xx_pce_microcode,
 	.pce_microcode_size	= ARRAY_SIZE(gsw1xx_pce_microcode),
 	.tag_protocol		= DSA_TAG_PROTO_MXL_GSW1XX,
@@ -732,6 +771,7 @@ static const struct gswip_hw_info gsw141_data = {
 	.mii_port_reg_offset	= -GSW1XX_MII_PORT,
 	.mac_select_pcs		= gsw1xx_phylink_mac_select_pcs,
 	.phylink_get_caps	= gsw1xx_phylink_get_caps,
+	.port_setup		= gsw1xx_port_setup,
 	.pce_microcode		= &gsw1xx_pce_microcode,
 	.pce_microcode_size	= ARRAY_SIZE(gsw1xx_pce_microcode),
 	.tag_protocol		= DSA_TAG_PROTO_MXL_GSW1XX,
diff --git a/drivers/net/dsa/lantiq/mxl-gsw1xx.h b/drivers/net/dsa/lantiq/mxl-gsw1xx.h
index 38e03c048a26c..8c0298b2b7663 100644
--- a/drivers/net/dsa/lantiq/mxl-gsw1xx.h
+++ b/drivers/net/dsa/lantiq/mxl-gsw1xx.h
@@ -110,6 +110,8 @@
 #define   GSW1XX_RST_REQ_SGMII_SHELL		BIT(5)
 /* RGMII PAD Slew Control Register */
 #define  GSW1XX_SHELL_RGMII_SLEW_CFG		0x78
+#define   RGMII_SLEW_CFG_DRV_TXC		BIT(2)
+#define   RGMII_SLEW_CFG_DRV_TXD		BIT(3)
 #define   RGMII_SLEW_CFG_RX_2_5_V		BIT(4)
 #define   RGMII_SLEW_CFG_TX_2_5_V		BIT(5)
 
-- 
2.52.0

Re: [PATCH net-next v4 2/2] net: dsa: mxl-gsw1xx: Support R(G)MII slew rate configuration

[Daniel Golle]

On Wed, Jan 07, 2026 at 10:00:17AM +0100, A. Sverdlin wrote:
> From: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> 
> Support newly introduced maxlinear,slew-rate-txc and
> maxlinear,slew-rate-txd device tree properties to configure R(G)MII
> interface pins' slew rate. It might be used to reduce the radiated
> emissions.
> 
> Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>

Reviewed-by: Daniel Golle <daniel@makrotopia.org>

Re: [PATCH net-next v4 2/2] net: dsa: mxl-gsw1xx: Support R(G)MII slew rate configuration

[Daniel Golle]

On Mon, Jan 12, 2026 at 12:18:58PM +0000, Daniel Golle wrote:
> On Wed, Jan 07, 2026 at 10:00:17AM +0100, A. Sverdlin wrote:
> > From: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> > 
> > Support newly introduced maxlinear,slew-rate-txc and
> > maxlinear,slew-rate-txd device tree properties to configure R(G)MII
> > interface pins' slew rate. It might be used to reduce the radiated
> > emissions.
> > 
> > Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> 
> Reviewed-by: Daniel Golle <daniel@makrotopia.org>
> 

Tested-by: Daniel Golle <daniel@makrotopia.org>

(got no means to measure if EMI actually decreases, but verified
registers are written as expected according to the new DT properties)