linux-kernel - Re: [PATCH] irqchip/apple-aic: Only handle PMC interrupt as FIQ when configured to fire FIQ

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Message-ID: <89307020-cc96-41e5-b0c9-998958b9844c@gmail.com>
Date: Sat, 18 Jan 2025 22:48:44 +0800
From: Nick Chan <towinchenmi@...il.com>
To: Sven Peter <sven@...npeter.dev>, Hector Martin <marcan@...can.st>,
 Alyssa Rosenzweig <alyssa@...enzweig.io>,
 Thomas Gleixner <tglx@...utronix.de>, Marc Zyngier <maz@...nel.org>,
 asahi@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Cc: stable@...r.kernel.org
Subject: Re: [PATCH] irqchip/apple-aic: Only handle PMC interrupt as FIQ when
 configured to fire FIQ


Sven Peter 於 2025/1/18 夜晚8:24 寫道:
> Hi,
>
>
> On Fri, Jan 17, 2025, at 18:02, Nick Chan wrote:
>> The CPU PMU in Apple SoCs can be configured to fire its interrupt in one
>> of several ways, and since Apple A11 one of the method is FIQ. Only handle
>> the PMC interrupt as a FIQ when the CPU PMU has been configured to fire
>> FIQs.
>>
>> Cc: stable@...r.kernel.org
>> Fixes: c7708816c944 ("irqchip/apple-aic: Wire PMU interrupts")
>> Signed-off-by: Nick Chan <towinchenmi@...il.com>
>> ---
>>  drivers/irqchip/irq-apple-aic.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/irqchip/irq-apple-aic.c 
>> b/drivers/irqchip/irq-apple-aic.c
>> index da5250f0155c..c3d435103d6d 100644
>> --- a/drivers/irqchip/irq-apple-aic.c
>> +++ b/drivers/irqchip/irq-apple-aic.c
>> @@ -577,7 +577,8 @@ static void __exception_irq_entry 
>> aic_handle_fiq(struct pt_regs *regs)
>>  						  AIC_FIQ_HWIRQ(AIC_TMR_EL02_VIRT));
>>  	}
>>
>> -	if (read_sysreg_s(SYS_IMP_APL_PMCR0_EL1) & PMCR0_IACT) {
>> +	if (read_sysreg_s(SYS_IMP_APL_PMCR0_EL1) &
>> +	    (FIELD_PREP(PMCR0_IMODE, PMCR0_IMODE_FIQ) | PMCR0_IACT)) {
> That's a somewhat unusual way to use FIELD_PREP and I'm not sure the
> expression even does what you want. It's true when only PMCR0_IACT is set and
> your commit description mentions that you only when to handle these when
> FIQ have been configured. Am I missing something here?
On a closer look the condition will evaluate to true when imode is between 7 and 4 inclusive and
PMCR0_IACT  is set. The intended behavior is to have it evaluate to true when imode is 4 and
PMCR0_IACT is set. Will send a v2.
>
>
> Best,
>
>
> Sven


Nick Chan