linux-kernel - Re: [PATCH v2 1/4] gpio: gpiolib: Allow GPIO IRQs to lazy disable

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Date:   Mon, 25 May 2020 13:55:37 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Maulik Shah <mkshah@...eaurora.org>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Hans Verkuil <hverkuil@...all.nl>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Marc Zyngier <maz@...nel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Evan Green <evgreen@...omium.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        MSM <linux-arm-msm@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Andy Gross <agross@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Doug Anderson <dianders@...omium.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Lina Iyer <ilina@...eaurora.org>, lsrao@...eaurora.org
Subject: Re: [PATCH v2 1/4] gpio: gpiolib: Allow GPIO IRQs to lazy disable

On Sat, May 23, 2020 at 7:11 PM Maulik Shah <mkshah@...eaurora.org> wrote:

> With 'commit 461c1a7d4733 ("gpiolib: override irq_enable/disable")' gpiolib
> overrides irqchip's irq_enable and irq_disable callbacks. If irq_disable
> callback is implemented then genirq takes unlazy path to disable irq.
>
> Underlying irqchip may not want to implement irq_disable callback to lazy
> disable irq when client drivers invokes disable_irq(). By overriding
> irq_disable callback, gpiolib ends up always unlazy disabling IRQ.
>
> Allow gpiolib to lazy disable IRQs by overriding irq_disable callback only
> if irqchip implemented irq_disable. In cases where irq_disable is not
> implemented irq_mask is overridden. Similarly override irq_enable callback
> only if irqchip implemented irq_enable otherwise irq_unmask is overridden.
>
> Fixes: 461c1a7d47 (gpiolib: override irq_enable/disable)
> Signed-off-by: Maulik Shah <mkshah@...eaurora.org>

I definitely want Hans Verkuils test and review on this, since it
is a usecase that he is really dependent on.

Also the irqchip people preferredly.

But it does seem to mop up my mistakes and fix this up properly!

So with some testing I'll be happy to merge it, even this one
patch separately if Hans can verify that it works.

Yours,
Linus Walleij