[PATCH 4/6] arm64: Add DTS support for FSL's LS2085A SoC

[Stuart Yoder]

> -----Original Message-----
> From: Kumar Gala [mailto:galak at codeaurora.org]
> Sent: Friday, August 15, 2014 10:26 AM
> To: Basu Arnab-B45036
> Cc: Mark Rutland; Sharma Bhupesh-B45370; arnd at arndb.de; Catalin Marinas;
> devicetree-discuss at lists.ozlabs.org; Will Deacon; Yoder Stuart-B08248;
> grant.likely at secretlab.ca; linux-arm-kernel at lists.infradead.org
> Subject: Re: [PATCH 4/6] arm64: Add DTS support for FSL's LS2085A SoC
> 
> 
> On Aug 15, 2014, at 10:21 AM, arnab.basu at freescale.com wrote:
> 
> >>>
> >>> +	cpus {
> >>> +		#address-cells = <2>;
> >>> +		#size-cells = <0>;
> >>> +
> >>> +		/* We have 4 clusters having 2 Cortex-A57 cores each */
> >>> +		cpu at 0 {
> >>> +			device_type = "cpu";
> >>> +			compatible = "arm,cortex-a57";
> >>> +			reg = <0x0 0x0>;
> >>> +			enable-method = "spin-table";
> >>> +			cpu-release-addr = <0x0 0x8000fff8>;
> >>> +		};
> >>
> >> I would strongly recommend having a unique cpu-release-addr for each CPU.
> >>
> >
> > This is more of a place holder, we intend to patch this address from U-Boot
> > and use individual release addresses for each CPU.
> 
> If you are going to patch it in u-boot, than why not just have u-boot add the
> property and drop it from here.
> 
> If you intend to keep it here, than make <0x0 0x0> and add a comment that says
> u-boot will fill it out

As I said to Mark re: the comment on having different release addresses
per CPU, we are just following existing practice from the existing
arch/arm64 device trees:
   apm-storm.dtsi
   foundation-v8.dts
   rtsm_ve-aemv8a.dts

I think one of the reasons the cpu-release-addr is not 0x0 is that 
UEFI had(?)/has(?) limited ability to do device tree fix ups.  It's
not a problem at all in u-boot, but there is some reason all
existing device trees have the same hardcoded address for all
CPUs.

So we want to do the standard/conventional thing here that will
allow are device trees to be used in more than u-boot.

Thanks,
Stuart