[PATCH] arm64: dts: imx8mq-phanbell: Fix Ethernet PHY post-reset duration

[PATCH] arm64: dts: imx8mq-phanbell: Fix Ethernet PHY post-reset duration

[Alifer Moraes]

i.MX8MQ Phanbell board uses Realtek RTL8211FD as Ethernet PHY.
Its datasheet states that the proper post reset duration should be at least 50 ms.

Fixes: f34d4bfab354 ("arm64: dts: imx8mq-phanbell: Add support for ethernet")
Signed-off-by: Alifer Moraes <alifer.wsdm@gmail.com>
---
 arch/arm64/boot/dts/freescale/imx8mq-phanbell.dts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/freescale/imx8mq-phanbell.dts b/arch/arm64/boot/dts/freescale/imx8mq-phanbell.dts
index 16ed13c44a47..06e248b95ada 100644
--- a/arch/arm64/boot/dts/freescale/imx8mq-phanbell.dts
+++ b/arch/arm64/boot/dts/freescale/imx8mq-phanbell.dts
@@ -207,7 +207,7 @@
 	phy-mode = "rgmii-id";
 	phy-reset-gpios = <&gpio1 9 GPIO_ACTIVE_LOW>;
 	phy-reset-duration = <10>;
-	phy-reset-post-delay = <30>;
+	phy-reset-post-delay = <50>;
 	phy-handle = <&ethphy0>;
 	fsl,magic-packet;
 	status = "okay";
-- 
2.17.1

Re: [PATCH] arm64: dts: imx8mq-phanbell: Fix Ethernet PHY post-reset duration

[Fabio Estevam]

Hi Alifer,

On Fri, Mar 6, 2020 at 7:41 AM Alifer Moraes <alifer.wsdm@gmail.com> wrote:
>
> i.MX8MQ Phanbell board uses Realtek RTL8211FD as Ethernet PHY.
> Its datasheet states that the proper post reset duration should be at least 50 ms.

The datasheet I found in the web states:

"The RTL8211F(I)/RTL8211FD(I) has a PHYRSTB pin to reset the chip. For
a complete PHY reset, this pin must be asserted low for at least 10ms
(Tgap in Figure 9) for the internal regulator. Wait for a further 30ms
(for internal circuits settling time) before accessing the PHY
register"

Where does the 50ms requirement come from? Do you have an updated
datasheet that says 50ms instead?

Please clarify.

Thanks

Re: [PATCH] arm64: dts: imx8mq-phanbell: Fix Ethernet PHY post-reset duration

[Fabio Estevam]

On Fri, Mar 13, 2020 at 1:32 PM Fabio Estevam <festevam@gmail.com> wrote:
>
> Hi Alifer,
>
> On Fri, Mar 6, 2020 at 7:41 AM Alifer Moraes <alifer.wsdm@gmail.com> wrote:
> >
> > i.MX8MQ Phanbell board uses Realtek RTL8211FD as Ethernet PHY.
> > Its datasheet states that the proper post reset duration should be at least 50 ms.
>
> The datasheet I found in the web states:
>
> "The RTL8211F(I)/RTL8211FD(I) has a PHYRSTB pin to reset the chip. For
> a complete PHY reset, this pin must be asserted low for at least 10ms
> (Tgap in Figure 9) for the internal regulator. Wait for a further 30ms
> (for internal circuits settling time) before accessing the PHY
> register"
>
> Where does the 50ms requirement come from? Do you have an updated
> datasheet that says 50ms instead?

Just found this one:
https://datasheet.lcsc.com/szlcsc/1909021205_Realtek-Semicon-RTL8211F-CG_C187932.pdf

Which says "Wait for at least 50ms* (for internal circuits settling
time) before accessing the PHY register.", so your patch is correct,
thanks.

This also fixes Ethernet in U-Boot, so:

Reviewed-by: Fabio Estevam <festevam@gmail.com>