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Date: Tue, 10 Feb 2015 16:00:13 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Jason Cooper <jason@lakedaemon.net>,
        Nicolas Ferre <nicolas.ferre@atmel.com>,
        Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>,
        Alexandre Belloni <alexandre.belloni@free-electrons.com>,
        Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Kumar Gala <galak@codeaurora.org>, devicetree@vger.kernel.org,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 2/5] irqchip: add virtual demultiplexer implementation
Message-ID: <20150210150013.GD7119@twins.programming.kicks-ass.net>
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On Thu, Jan 29, 2015 at 11:33:37AM +0100, Boris Brezillon wrote:
> +#ifdef CONFIG_VIRT_IRQ_DEMUX_CHIP
> +/**
> + * struct irq_chip_virt_demux - Dumb demultiplexer irq chip data structure

s/Dumb/Virtual/ ?

> + * @domain:		irq domain pointer
> + * @available:		Bitfield of valid irqs
> + * @unmasked:		Bitfield containing irqs status
> + * @flags:		irq_virt_demux_flags flags
> + * @src_irq:		irq feeding the virt demux chip
> + *
> + * Note, that irq_chip_generic can have multiple irq_chip_type
> + * implementations which can be associated to a particular irq line of
> + * an irq_chip_generic instance. That allows to share and protect
> + * state in an irq_chip_generic instance when we need to implement
> + * different flow mechanisms (level/edge) for it.

This seems like a copy/paste from struct irq_chip_generic; it seems not
relevant, seeing how irq_chip_virt_demux does not even have an
irq_chip_type pointer list.

Also, with a demuxer like this, we're bound to whatever flow type its
host is, no?

> +# Dumb interrupt demuxer chip implementation

s/Dumb/Virtual/ ?

> +#ifdef CONFIG_VIRT_IRQ_DEMUX_CHIP
> +/**
> + *	handle_virt_demux_irq - Dumb demuxer irq handle function.

idem

> + *	@irq:	the interrupt number
> + *	@desc:	the interrupt description structure for this irq
> + *
> + *	Dumb demux interrupts are sent from a demultiplexing interrupt handler

idem

> + *	which is not able to decide which child interrupt handler should be
> + *	called.
> + *
> + *	Note: The caller is expected to handle the ack, clear, mask and
> + *	unmask issues if necessary.
> + */

If we're calling multiple handlers, how can they all do this and not
collide?

Over all it looks good -- in as far as my (admittedly stale IRQ
braincells) go.

I'll go queue up these bits, if you could send me a delta patch
addressing these 'minor' comment issues?