[PATCH 3/7] arm64: dts: imx8mp-venice-gw702x: reduce RGMII CLK drive strength

Tim Harvey posted 7 patches 2 weeks, 1 day ago
[PATCH 3/7] arm64: dts: imx8mp-venice-gw702x: reduce RGMII CLK drive strength
Posted by Tim Harvey 2 weeks, 1 day ago
The i.MX8M Plus EQOS RGMII tracelength is less than 1in and does not
require a x6 drive strength. Reduce the CLK drive strength to x1 for
better emissions.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
---
 arch/arm64/boot/dts/freescale/imx8mp-venice-gw702x.dtsi | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/freescale/imx8mp-venice-gw702x.dtsi b/arch/arm64/boot/dts/freescale/imx8mp-venice-gw702x.dtsi
index a1232a4f8485..dd9eeb3479fd 100644
--- a/arch/arm64/boot/dts/freescale/imx8mp-venice-gw702x.dtsi
+++ b/arch/arm64/boot/dts/freescale/imx8mp-venice-gw702x.dtsi
@@ -462,7 +462,7 @@ MX8MP_IOMUXC_ENET_TD1__ENET_QOS_RGMII_TD1		0x16
 			MX8MP_IOMUXC_ENET_TD2__ENET_QOS_RGMII_TD2		0x16
 			MX8MP_IOMUXC_ENET_TD3__ENET_QOS_RGMII_TD3		0x16
 			MX8MP_IOMUXC_ENET_TX_CTL__ENET_QOS_RGMII_TX_CTL		0x16
-			MX8MP_IOMUXC_ENET_TXC__CCM_ENET_QOS_CLOCK_GENERATE_TX_CLK	0x16
+			MX8MP_IOMUXC_ENET_TXC__CCM_ENET_QOS_CLOCK_GENERATE_TX_CLK	0x0
 		>;
 	};
 
-- 
2.25.1
Re: [PATCH 3/7] arm64: dts: imx8mp-venice-gw702x: reduce RGMII CLK drive strength
Posted by Peng Fan 2 weeks ago
Hi Tim,

On Tue, Sep 16, 2025 at 08:32:12AM -0700, Tim Harvey wrote:
>The i.MX8M Plus EQOS RGMII tracelength is less than 1in and does not
>require a x6 drive strength. Reduce the CLK drive strength to x1 for
>better emissions.
>
>Signed-off-by: Tim Harvey <tharvey@gateworks.com>
>---
> arch/arm64/boot/dts/freescale/imx8mp-venice-gw702x.dtsi | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/arch/arm64/boot/dts/freescale/imx8mp-venice-gw702x.dtsi b/arch/arm64/boot/dts/freescale/imx8mp-venice-gw702x.dtsi
>index a1232a4f8485..dd9eeb3479fd 100644
>--- a/arch/arm64/boot/dts/freescale/imx8mp-venice-gw702x.dtsi
>+++ b/arch/arm64/boot/dts/freescale/imx8mp-venice-gw702x.dtsi
>@@ -462,7 +462,7 @@ MX8MP_IOMUXC_ENET_TD1__ENET_QOS_RGMII_TD1		0x16
> 			MX8MP_IOMUXC_ENET_TD2__ENET_QOS_RGMII_TD2		0x16
> 			MX8MP_IOMUXC_ENET_TD3__ENET_QOS_RGMII_TD3		0x16
> 			MX8MP_IOMUXC_ENET_TX_CTL__ENET_QOS_RGMII_TX_CTL		0x16
>-			MX8MP_IOMUXC_ENET_TXC__CCM_ENET_QOS_CLOCK_GENERATE_TX_CLK	0x16
>+			MX8MP_IOMUXC_ENET_TXC__CCM_ENET_QOS_CLOCK_GENERATE_TX_CLK	0x0

You also changed FSEL from 2 to 0. So I would add this in commit that if this
matches:
Since TXC is not a high frequency clock, use slow slew rate for lower emissions
and better signal quality

Regards
Peng
> 		>;
> 	};
> 
>-- 
>2.25.1
>