On 1/3/21 6:16 AM, Marc Zyngier wrote:

[dropped linux-sunxi@googlegroups.com, which seems to be a closed ML]

On Sun, 03 Jan 2021 10:30:51 +0000,
Samuel Holland [off-list ref] wrote:

quoted

Allwinner sun6i/sun8i/sun50i SoCs (A31 and newer) have two interrupt
controllers: GIC and R_INTC. GIC does not support wakeup. R_INTC handles
the external NMI pin, and provides 32+ IRQs to the ARISC. The first 16
of these correspond 1:1 to a block of GIC IRQs starting with the NMI.
The last 13-16 multiplex the first (up to) 128 GIC SPIs.

This series replaces the existing chained irqchip driver that could only
control the NMI, with a stacked irqchip driver that also provides wakeup
capability for those multiplexed SPI IRQs. The idea is to preconfigure
the ARISC's IRQ controller, and then the ARISC firmware knows to wake up
as soon as it receives an IRQ. It can also decide how deep it can
suspend based on the selected wakeup IRQs.

Out of curiosity, how do you plan to communicate dynamic configuration
of IRQs to the ARISC? We recently went through this with some TI
stuff, and the result a bit awkward (the arm64 side configures
interrupts that are not visible to the kernel, but only to the
co-processors).

Assuming by "dynamic" you mean while Linux is running, I don't plan to
communicate anything. As far as I'm concerned, the driver is feature-complete
after this patch series. The ARISC firmware does not use the interrupt
controller (or any other shared peripherals) while Linux is running. It sits in
a tight loop polling its side of the mailbox, waiting for a
hotplug/suspend/poweroff/reboot command.

I wondered whether you had other ideas...

Sorry, I guess not. We tried to avoid using the ARISC for long enough that
anything that can have a native Linux driver has one. So the ARISC firmware has
nothing to do while Linux is running. (This is in comparison to the vendor BSP,
where some peripherals are only accessed through their firmware.)

Samuel

Thanks,

	M.

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel