On Tue, Sep 22, 2020 at 10:32:06AM +0200, Arnd Bergmann wrote:

On Tue, Sep 22, 2020 at 8:15 AM Manivannan Sadhasivam
[off-list ref] wrote:

quoted

On Mon, Sep 21, 2020 at 11:43:02PM -0300, Matheus Castello wrote:

quoted

+     /* Labrador v3 firmware does not support PSCI */

Oops. This is unfortunate... I'm not sure if this is even acceptable for
ARM64 machines.

Let me add Olof and Arnd...

Adding Catalin and Will for additional input as well, this is more their
area than ours.

I don't think we have formalized this as a policy, but we clearly don't
want new boards to use the spin table hack. As there are other
boards using psci on the same chip, I don't think this is a
hardware bug.

I fully agree, we shouldn't allow new boards to use the spin-table
method unless EL3 is missing on the CPU implementation (not the case
here; only the APM hardware has this issue). Unfortunately we missed
another platform with A53, see commit bc66392d8258 ("arm64: dts: fsl:
Add device tree for S32V234-EVB").

The kernel relies on firmware for other things (power management, errata
workarounds), so an SMC calling convention compliant firmware is highly
recommended. I also don't see why it would be that hard to add PSCI.
Even if you don't port something like Trusted Firmware, U-Boot has basic
support for PSCI.

So from my perspective, NAK on this patch.

I'm tempted to also modify smp_spin_table_cpu_init() to print a big
warning and return an error if this is attempted on new platforms. IOW,
we make it a policy from now on.

-- 
Catalin

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