Re: [PATCH 18/18] arm64: apple: Add initial Mac Mini 2020 (M1) devicetree

[Marc Zyngier <maz@kernel.org>]

On 2021-02-04 20:39, Hector Martin wrote:
> This currently supports:
> 
> * SMP (via spin-tables)
> * AIC IRQs
> * Serial (with earlycon)
> * Framebuffer
> 
> A number of properties are dynamic, and based on system firmware
> decisions that vary from version to version. These are expected
> to be filled in by the loader.
> 
> Signed-off-by: Hector Martin <marcan@marcan.st>
> ---

[...]

> +	timer {
> +		compatible = "arm,armv8-timer";
> +		interrupt-parent = <&aic>;
> +		interrupts = <AIC_FIQ 0 IRQ_TYPE_LEVEL_HIGH>,
> +				<AIC_FIQ 0 IRQ_TYPE_LEVEL_HIGH>,
> +				<AIC_FIQ 1 IRQ_TYPE_LEVEL_HIGH>,
> +				<AIC_FIQ 0 IRQ_TYPE_LEVEL_HIGH>;

This unfortunately doesn't match the binding, which doesn't cater
for systems without a secure physical timer, nor allows the description
of the EL2 virtual timer.

You should also have *different* interrupts for EL1 and EL2 timers,
although this is all a lie...

Looking at the only similar case, XGene lies about the secure timer
(it doesn't have any), and of course doesn't have an EL2 virtual
timer (ARMv8.0 only).

A sensible course of action could be to update the binding to at least:

- tell the kernel that there is no secure physical timer (and that
   the interrupt should be ignored)
- introduce a 5th possible interrupt for the EL2 virtual timer.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...