Re: [PATCH] ARM: dts: aspeed-g6: add pcie-lpc and pcie-kcs4

[Grégoire Layet]

> > diff --git a/arch/arm/boot/dts/aspeed/aspeed-g6.dtsi b/arch/arm/boot/dts/aspeed/aspeed-g6.dtsi
> > index 56bb3b0444f7..ac351f01048f 100644
> > --- a/arch/arm/boot/dts/aspeed/aspeed-g6.dtsi
> > +++ b/arch/arm/boot/dts/aspeed/aspeed-g6.dtsi
> > @@ -658,6 +658,21 @@ ibt: ibt@140 {
> >                               };
> >                       };
> >
> > +                     pcie_lpc: pcie-lpc@1e789800 {
>
> lpc@1e789000 already maps 0x1e789000-0x1e78a000 and 0x1e789914 falls inside it,

I agree that there is an overlap in address space in my patch.
I will fix this in a new revision.

> so you're describing a second `ast2600-lpc-v2` node which is unnecessary.
>
> Suggestion: Merge pcie_kcs4 into lpc@1e789000 and use 914 as offset. That way
> you don't accidentally cause an overlap for the devices if you describe more in
> the future.

The 'kcs_bmc_aspeed' driver has the kcs channels address hard-coded.
If the 'reg' property does not contain the three addresses used by one
of the four channels, the driver returns -EINVAL.
So having a pcie-kcs4 with regs 0x914, 0x918 and 0x91c doesn't work.

This is why a second LPC node was added, for the pcie-kcs4 to have
regs 0x114, 0x118 and 0x11c;

I know we should write device tree sources based on hardware rather
than around driver limitations.
Changing how the driver behaves seems excessive for supporting KCS over PCIe.
I think a point can be made that the LPC over PCIe is a different LPC bus.

Regards,
Grégoire