Re: [RFC PATCH v1 1/1] mailbox: arm_mhuv3: Keep the combined IRQ enabled during system suspend

[Sudeep Holla <sudeep.holla@kernel.org>]

On Wed, Sep 30, 2026 at 11:36:57AM +0800, Finley Xiao wrote:
> When MHUv3 is used as the SCMI mailbox transport (arm,scmi-mailbox),
> SCMI clock and power-domain operations still need to work in the noirq
> phase of system suspend: genpd may power off a device's parent domain
> from genpd_suspend_noirq(), which issues scmi_clock_config_set() /
> scmi_power_state_set() and waits for the firmware reply via the mailbox
> RX IRQ.
> 
> However, dpm_suspend_noirq() calls suspend_device_irqs() before running
> the suspend_noirq callbacks, so the combined interrupts are already
> masked at that point and the SCMI transfer times out while waiting for
> the reply.
> 
> Both the PBX and MBX combined interrupts are requested as threaded
> IRQs with only IRQF_ONESHOT. The MBX combined IRQ must stay enabled so
> that firmware replies are delivered, and the PBX combined IRQ, used
> for txdone by IRQ when not in polling mode, needs the same treatment.
> 
> IRQ threads are not frozen during system suspend, so with
> IRQF_NO_SUSPEND the threaded combined-IRQ handlers still run in the
> noirq phase.
> 
> Add IRQF_NO_SUSPEND to the MHUv3 combined IRQ registrations so that
> SCMI remains functional throughout the suspend/resume cycle.
>

Looks good to me. Just to confirm, the expectation is to just have the
IRQs functional during suspend/resume cycle only and *not to wake up* the
system right ? If you need wakeup, you need to do more work.

For this change,

Reviewed-by: Sudeep Holla <sudeep.holla@kernel.org>

Jassi,

Please pick this up for next cycle when you are at it. Thanks!

-- 
Regards,
Sudeep