Re: [PATCH 5/5] ARM: dts: aspeed: Add Facebook Darwin (AST2600) BMC

Tao Ren
2025-07-03T22:15:48Z

On Thu, Jul 03, 2025 at 09:58:48AM +0200, Andrew Lunn wrote:
> > > How do RGMII delays work? Connections to switches have to be handled
> > > different to PHYs, to avoid double delays. But is there extra long
> > > clock lines? Or are you expecting the switch to add the delays?
> > >
> > > Andrew
> >
> > Hi Andrew,
> >
> > The delays are introduced in BMC MAC by setting SCU control registers in
> > u-boot. The delays on the switch side are disabled.
>
> Sorry, but not acceptable. This is something i've been NACKing Aspeed
> DT patches for. You need the MAC driver to interpret the phy-mode and
> program the SCU control register as needed.
>
> Since you have the MAC introducing the delays, you want phy-mode
> 'rgmii-id'.
>
> If you want to submit some DT now, drop the ethernet node. This is
> what others have been doing while waiting for Aspeed to fix their MAC
> driver. Having said that, i've not seen any progress from Aspeed, so
> it either needs their customers to apply more pressure, or somebody in
> the community to just fix it and submit patches.
>
> Andrew

Hi Andrew,

Got it, and thanks for sharing the context.

I will reach out to ASPEED offline to see if they are actively working
on the MAC fix, or if I have enough knowledge to work out the patch.

Thanks,

Tao