linux-kernel - Re: SOC-specific action for irq_set

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Message-ID: <alpine.DEB.2.11.1607200759230.3564@nanos>
Date:	Wed, 20 Jul 2016 08:28:35 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Sören Brinkmann <soren.brinkmann@...inx.com>
cc:	Jason Cooper <jason@...edaemon.net>,
	Marc Zyngier <marc.zyngier@....com>,
	Michal Simek <michal.simek@...inx.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: SOC-specific action for irq_set_wake

On Tue, 19 Jul 2016, Sören Brinkmann wrote:
> we are working on the PM solution for Zynq MPSOC and ran into some
> problem when setting the wake source.
> 
> The situation is that when the A53 is in suspend, the GIC(v2) may be
> powered down. In that state a companion core is handling wake
> events/IRQs, but we expect the OS/Linux to notify the companion core
> about what device/IRQ is a wake up source. Hence, my idea was to capture
> enabling/disabling wake IRQs in our platform PM code and then
> communicate with the FW as needed during suspend operations. The problem
> is: I don't see a good way to notify the platform code about these
> events.
> 
> My ideas were:
> 1. Use the irq_chip irq_set_wake function
>   My thought was to implement the irq_set_wake function in a
>   SOC-specific way (could even be generic and call some notifier chain or

Don't even think about notifier chains.

>   similar) to notify the platform PM code when a device/IRQ is
>   enabled/disabled as wake up source.
>   My problem is that the SKIP_IRQ_SET_WAKE flag is set in the generic
>   driver (drivers/irqchip/irq-gic.c) and platforms cannot implement
>   irq_set_wake without changes in the common code.

So and because it requires changes in the common code you think aboiut
notifiers and other absurdities. Come on, common code is not a sacred cow. It
can be modified and if you need for your particular platform that
SKIP_IRQ_SET_WAKE is cleared, then there are a gazillion of sane ways to do
that.

Thanks,

	tglx