linux-kernel - Re: [PATCH 6/7] gpio: brcmstb: consolidate interrupt domains

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Date:   Tue, 3 Oct 2017 20:03:12 -0700
From:   Gregory Fong <gregory.0xf0@...il.com>
To:     Doug Berger <opendmb@...il.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Brian Norris <computersforpeace@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        bcm-kernel-feedback-list <bcm-kernel-feedback-list@...adcom.com>,
        linux-gpio@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 6/7] gpio: brcmstb: consolidate interrupt domains

Hi Doug,

On Fri, Sep 29, 2017 at 8:40 PM, Doug Berger <opendmb@...il.com> wrote:
> The GPIOLIB IRQ chip helpers were very appealing, but badly broke
> the 1:1 mapping between a GPIO controller's device_node and its
> interrupt domain.

Out of curiosity, what sort of problems have you seen from this?

>
> This commit consolidates the per bank irq domains to a version
> where we have one larger interrupt domain per GPIO controller
> instance spanning multiple GPIO banks.

This works (and is reminiscent to my initially submitted
implementation at [1]), but I think it might make sense to keep as-is
(using the gpiolib irqchip helpers), and instead allocate an irqchip
fwnode per bank and use to_of_node() to set it as the of_node for the
gpiochip before calling gpiochip_irqchip_add().  OTOH, that capability
might go away...

Linus, can you comment on the FIXME in gpiochip_irqchip_add_key() that
says "get rid of this and use gpiochip->parent->of_node everywhere"?
It seems like it would still be beneficial to be able to override the
associated node for a gpiochip, since that's what's used for the
irqdomain, but if that's going away, obviously we don't want to start
using that now.

Thanks,
Gregory

[1] https://patchwork.kernel.org/patch/6347811/