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

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Message-ID: <CACRpkdY3pJVvAi_a=pVVQQbQyA3_b=o2pJqb5W8Wivp-SSy+tA@mail.gmail.com>
Date:   Wed, 27 May 2020 15:56:16 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Hans Verkuil <hverkuil@...all.nl>,
        Russell King <linux@...linux.org.uk>
Cc:     Maulik Shah <mkshah@...eaurora.org>,
        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 Wed, May 27, 2020 at 12:38 PM Hans Verkuil <hverkuil@...all.nl> wrote:

> However, I discovered that patch 256efaea1fdc ("gpiolib: fix up emulated
> open drain outputs") broke the cec-gpio driver on the Raspberry Pi starting
> with kernel v5.5.
>
> The CEC pin is an open drain pin that is used in both input and output
> directions and has an interrupt (which is of course disabled while in
> output mode).
>
> With this patch the interrupt can no longer be requested:
>
> [    4.157806] gpio gpiochip0: (pinctrl-bcm2835): gpiochip_lock_as_irq: tried to flag a GPIO set as output for IRQ
>
> [    4.168086] gpio gpiochip0: (pinctrl-bcm2835): unable to lock HW IRQ 7 for IRQ
> [    4.175425] genirq: Failed to request resources for cec-gpio@7 (irq 79) on irqchip pinctrl-bcm2835
> [    4.184597] cec-gpio: probe of cec-gpio@7 failed with error -5

There is nothing conceptually wrong with that patch so I think we
need to have the irqchip code check if it is input *OR* open drain.

I'll send a separate patch for this, it should be an easy fix.

Yours,
Linus Walleij