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@xxxxxxxxx> wrote:
>
> Hi Alifer,
>
> On Fri, Mar 6, 2020 at 7:41 AM Alifer Moraes <alifer.wsdm@xxxxxxxxx> 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@xxxxxxxxx>