linux-kernel - Re: [PATCH v3 22/26] irqchip/apple-aic: Drop support for custom PMU irq partitions

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Message-ID: <87jz1qxmk5.wl-maz@kernel.org>
Date: Mon, 22 Sep 2025 21:24:42 +0100
From: Marc Zyngier <maz@...nel.org>
To: Sven Peter <sven@...nel.org>
Cc: linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-acpi@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Mark Rutland
 <mark.rutland@....com>,
	Will Deacon <will@...nel.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Saravana Kannan <saravanak@...gle.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Janne Grunau
 <j@...nau.net>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	James Clark <james.clark@...aro.org>,
	Jonathan Cameron <jonathan.cameron@...wei.com>
Subject: Re: [PATCH v3 22/26] irqchip/apple-aic: Drop support for custom PMU irq partitions

On Mon, 22 Sep 2025 19:43:40 +0100,
Sven Peter <sven@...nel.org> wrote:
> 
> On 22.09.25 10:28, Marc Zyngier wrote:
> > Similarly to what has been done for GICv3, drop the irq partitioning
> > support from the AIC driver, effectively merging the two per-cpu
> > interrupts for the PMU.
> > 
> > Signed-off-by: Marc Zyngier <maz@...nel.org>
> > ---
> 
> Reviewed-by: Sven Peter <sven@...nel.org>
> 
> 
> >   drivers/irqchip/irq-apple-aic.c | 28 +++++++---------------------
> >   1 file changed, 7 insertions(+), 21 deletions(-)
> > 
> > diff --git a/drivers/irqchip/irq-apple-aic.c b/drivers/irqchip/irq-apple-aic.c
> > index cb8b6f40ce8d3..6305d25b9e77b 100644
> > --- a/drivers/irqchip/irq-apple-aic.c
> > +++ b/drivers/irqchip/irq-apple-aic.c
> > @@ -578,16 +578,9 @@ static void __exception_irq_entry aic_handle_fiq(struct pt_regs *regs)
> >   	}
> >     	if ((read_sysreg_s(SYS_IMP_APL_PMCR0_EL1) & (PMCR0_IMODE |
> > PMCR0_IACT)) ==
> > -			(FIELD_PREP(PMCR0_IMODE, PMCR0_IMODE_FIQ) | PMCR0_IACT)) {
> > -		int irq;
> > -		if (cpumask_test_cpu(smp_processor_id(),
> > -				     &aic_irqc->fiq_aff[AIC_CPU_PMU_P]->aff))
> > -			irq = AIC_CPU_PMU_P;
> > -		else
> > -			irq = AIC_CPU_PMU_E;
> > +			(FIELD_PREP(PMCR0_IMODE, PMCR0_IMODE_FIQ) | PMCR0_IACT))
> >   		generic_handle_domain_irq(aic_irqc->hw_domain,
> > -					  AIC_FIQ_HWIRQ(irq));
> > -	}
> > +					  AIC_FIQ_HWIRQ(AIC_CPU_PMU_P));
> 
> Probably one of the most confusing diffs for a change that's actually
> fairly simple that the diff algorithm generated! I was only able to
> tell what's going on by looking at the file after applying this.

It appears that all 4 algorithms (myers, minimal, patience and
histogram) give the exact same resolution for these two hunks.

It would have been easier to read if I had rewritten the 'if'
statement to be on a single line (and moved the whole field business
to a helper), but I went for the smallest possible change. My bad,

Thanks for the review!

	M.

-- 
Jazz isn't dead. It just smells funny.