linux-kernel - Re: [PATCH] pinctrl: qcom: Move clearing pending IRQ to .irq_request

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Message-ID: <20201110212813.GF807@yoga>
Date:   Tue, 10 Nov 2020 15:28:13 -0600
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Maulik Shah <mkshah@...eaurora.org>,
        Andy Gross <agross@...nel.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>,
        "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>," 
        <dianders@...omium.org>, Stephen Boyd <swboyd@...omium.org>,
        Evan Green <evgreen@...omium.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Lina Iyer <ilina@...eaurora.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] pinctrl: qcom: Move clearing pending IRQ to
 .irq_request_resources callback

On Tue 10 Nov 07:31 CST 2020, Linus Walleij wrote:

> On Thu, Nov 5, 2020 at 8:38 AM Maulik Shah <mkshah@...eaurora.org> wrote:
> 
> > When GPIOs that are routed to PDC are used as output they can still latch
> > the IRQ pending at GIC. As a result the spurious IRQ was handled when the
> > client driver change the direction to input to starts using it as IRQ.
> >
> > Currently such erroneous latched IRQ are cleared with .irq_enable callback
> > however if the driver continue to use GPIO as interrupt and invokes
> > disable_irq() followed by enable_irq() then everytime during enable_irq()
> > previously latched interrupt gets cleared.
> >
> > This can make edge IRQs not seen after enable_irq() if they had arrived
> > after the driver has invoked disable_irq() and were pending at GIC.
> >
> > Move clearing erroneous IRQ to .irq_request_resources callback as this is
> > the place where GPIO direction is changed as input and its locked as IRQ.
> >
> > While at this add a missing check to invoke msm_gpio_irq_clear_unmask()
> > from .irq_enable callback only when GPIO is not routed to PDC.
> >
> > Fixes: e35a6ae0eb3a ("pinctrl/msm: Setup GPIO chip in hierarchy")
> > Signed-off-by: Maulik Shah <mkshah@...eaurora.org>
> 
> This looks critical so I applied it for fixes so we get some
> rotation in linux-next.
> 
> If Bjorn has other opinions he will tell us :)
> 

No objections, the patch looks reasonable to me.

Acked-by: Bjorn Andersson <bjorn.andersson@...aro.org>

Regards,
Bjorn