linux-kernel - Re: [PATCH] irqchip/irq-brcmstb-l2: Avoid saving mask on shutdown

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Message-ID: <87mspiu19l.ffs@tglx>
Date: Wed, 24 Apr 2024 19:19:18 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: Florian Fainelli <f.fainelli@...il.com>, Florian Fainelli
 <florian.fainelli@...adcom.com>, linux-kernel@...r.kernel.org
Cc: opendmb@...il.com, Tim Ross <tim.ross@...adcom.com>, Broadcom internal
 kernel review list <bcm-kernel-feedback-list@...adcom.com>, "open
 list:BROADCOM BMIPS MIPS ARCHITECTURE" <linux-mips@...r.kernel.org>,
 "moderated list:BROADCOM BCM7XXX ARM ARCHITECTURE"
 <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] irqchip/irq-brcmstb-l2: Avoid saving mask on shutdown

On Wed, Apr 24 2024 at 09:50, Florian Fainelli wrote:
> On 4/22/24 16:45, Thomas Gleixner wrote:
>> On Mon, Apr 22 2024 at 15:26, Florian Fainelli wrote:
>>> On 4/22/24 14:29, Thomas Gleixner wrote:
>>>>> +	if (save)
>>>>> +		b->saved_mask = irq_reg_readl(gc, ct->regs.mask);
>>>>
>>>> what's the conditional actually buying you except more complex code?
>>>
>>> Not much this is an optimization that is simple to carry out. There can
>>> be dozens of such L2 interrupt controllers in a given system and the
>>> MMIO accesses start adding up eventually.
>> 
>> I'm impressed by saving ~12 microseconds per one dozen of interrupt
>> controllers on system shutdown :)
>
> I know, right? More seriously are you willing to take that patch, should 
> I write a better justification?

I don't have real objections other than rolling my eyes, but a better
justification would be useful.