-----Original Message-----
From: Catalin Marinas [mailto:catalin.marinas at arm.com]
Sent: Friday, August 15, 2014 10:29 AM
To: Sharma Bhupesh-B45370
Cc: Yoder Stuart-B08248; devicetree-discuss at lists.ozlabs.org; Will Deacon;
arnd at arndb.de; grant.likely at secretlab.ca; linux-arm-kernel at lists.infradead.org;
Basu Arnab-B45036
Subject: Re: [PATCH 4/6] arm64: Add DTS support for FSL's LS2085A SoC

On Fri, Aug 15, 2014 at 03:31:48PM +0100, bhupesh.sharma at freescale.com wrote:

quoted

quoted

On Fri, Aug 15, 2014 at 01:53:13PM +0100, Stuart Yoder wrote:

quoted

quoted

On Fri, Aug 15, 2014 at 10:49:13AM +0100, Bhupesh Sharma wrote:

quoted

+	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>;
+		};

Why not PSCI?

It simply is where we are today-- we don't have functioning PSCI yet
but plan to get there over time.

Thanks for clarification.

quoted

All the existing device trees
in arch/arm64 use "spin-table", so it seems that other platforms are
in the same situation:
   apm-storm.dtsi

Not possible because there is no EL3 mode on the CPU implementation.

quoted

   foundation-v8.dts
   rtsm_ve-aemv8a.dts

These work with the latest boot wrapper (which overrides the DT nodes and
passes the PSCI information).

Right. We are working on our PSCI handler implementation in EL3 and the spin-

table

quoted

approach it something we are currently supporting on the simulator model

using

quoted

u-boot bootloader setting up the spin-tables.

Our patches for implementing spin-table approach in armv8 u-boot are already

under

quoted

review and corresponding rework [1].

It would be better if you helped with this effort to bring PSCI to
U-Boot (ARMv7 currently but easy to port to AArch64):

https://git.kernel.org/cgit/linux/kernel/git/maz/u-boot.git/log/?h=wip/psci-v4
https://git.kernel.org/cgit/linux/kernel/git/maz/u-boot.git/log/?h=wip/psci-v4-
a20

Is the intent to eventually purge the device trees of enable-method/cpu-release-addr
and have that set by the boot firmware?  Or, keep the spin-table method 
around as a least common denominator mechanism and override it when
necessary?   Wondering what the longer term thinking is...

Thanks,
Stuart