Hi,

On 26/02/18 15:54, Samuel Holland wrote:

On 02/26/18 03:26, Maxime Ripard wrote:

quoted

On Fri, Feb 23, 2018 at 11:22:06PM +0800, Icenowy Zheng wrote:

quoted

quoted

quoted

+	psci {
+		compatible = "arm,psci-0.2";
+		method = "smc";
+	};

Is it needed? The bootloader should fill it with whatever version it
has, shouldn't it?

But we now use ATF rather than U-Boot PSCI. U-Boot will not fill ATF
info.

See A64/H5 device trees.

So if the PSCI version implemented in ATF ever changes, we would have
to update all the DT everywhere, but only if you're running the new
version?

Yes but no. PSCI 1.0 is generally backward compatible with PSCI 0.2. In fact,
the Linux driver treats them exactly the same:

        { .compatible = "arm,psci-0.2", .data = psci_0_2_init},
        { .compatible = "arm,psci-1.0", .data = psci_0_2_init},

Yeah, it's actually unclear why we have that new compatible name in the
first place, since starting with PSCI v0.2 the version can be perfectly
read using the mandatory PSCI_VERSION call. And DT aims to only cover
things that are not discoverable.

For the H6, however, the oldest ATF source available (which I believe was the
one in use during bringup) is based on mainline 1.4, and is already at PSCI
version 1.1:

[    0.000000] psci: probing for conduit method from DT.
[    0.000000] psci: PSCIv1.1 detected in firmware.
[    0.000000] psci: Using standard PSCI v0.2 function IDs
[    0.000000] psci: MIGRATE_INFO_TYPE not supported.

So we could go ahead and bump the compatible to "arm,psci-1.0".

I'd rather leave it at "arm,psci-0.2", since this improves compatibility
to other OSes or DT users.

Cheers,
Andre.