[PATCH v2 4/7] arm64: dts: imx8mm-venice-gw700x: reduce RGMII CLK drive strength

Tim Harvey posted 7 patches 1 week, 6 days ago
[PATCH v2 4/7] arm64: dts: imx8mm-venice-gw700x: reduce RGMII CLK drive strength
Posted by Tim Harvey 1 week, 6 days ago
The i.MX8M Mini FEC RGMII tracelength is less than 1in and does not
require a x6 drive strength. Reduce the CLK drive strength to x1 for
lower emissions. Additionally since TXC is not a high frequency clock,
use slow slew rate (FSEL=0) for lower emmissions and improved signal
quality.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
---
v2: add FSEL detail to log (Peng)
---
 arch/arm64/boot/dts/freescale/imx8mm-venice-gw700x.dtsi | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/freescale/imx8mm-venice-gw700x.dtsi b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw700x.dtsi
index baf46fe28133..dca213c85cc3 100644
--- a/arch/arm64/boot/dts/freescale/imx8mm-venice-gw700x.dtsi
+++ b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw700x.dtsi
@@ -446,7 +446,7 @@ MX8MM_IOMUXC_ENET_RD3_ENET1_RGMII_RD3		0x91
 			MX8MM_IOMUXC_ENET_RD2_ENET1_RGMII_RD2		0x91
 			MX8MM_IOMUXC_ENET_RD1_ENET1_RGMII_RD1		0x91
 			MX8MM_IOMUXC_ENET_RD0_ENET1_RGMII_RD0		0x91
-			MX8MM_IOMUXC_ENET_TXC_ENET1_RGMII_TXC		0x1f
+			MX8MM_IOMUXC_ENET_TXC_ENET1_RGMII_TXC		0x0
 			MX8MM_IOMUXC_ENET_RXC_ENET1_RGMII_RXC		0x91
 			MX8MM_IOMUXC_ENET_RX_CTL_ENET1_RGMII_RX_CTL	0x91
 			MX8MM_IOMUXC_ENET_TX_CTL_ENET1_RGMII_TX_CTL	0x1f
-- 
2.25.1
Re: [PATCH v2 4/7] arm64: dts: imx8mm-venice-gw700x: reduce RGMII CLK drive strength
Posted by Peng Fan 1 week, 6 days ago
On Thu, Sep 18, 2025 at 08:44:48AM -0700, Tim Harvey wrote:
>The i.MX8M Mini FEC RGMII tracelength is less than 1in and does not
>require a x6 drive strength. Reduce the CLK drive strength to x1 for
>lower emissions. Additionally since TXC is not a high frequency clock,
>use slow slew rate (FSEL=0) for lower emmissions and improved signal
>quality.
>
>Signed-off-by: Tim Harvey <tharvey@gateworks.com>

Reviewed-by: Peng Fan <peng.fan@nxp.com>