linux-kernel - Re: [PATCH v4 07/13] i2c: acpi: Use ACPI wake capability bit to set wake

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAHQZ30C3Wsqbwnpn+9tP2DCDdtMGOqOZ8di77agDcLM7idWxuQ@mail.gmail.com>
Date:   Wed, 21 Sep 2022 09:18:34 -0600
From:   Raul Rangel <rrangel@...omium.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Linux ACPI <linux-acpi@...r.kernel.org>,
        linux-input <linux-input@...r.kernel.org>,
        Tim Van Patten <timvp@...gle.com>,
        Hans de Goede <hdegoede@...hat.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        "Limonciello, Mario" <mario.limonciello@....com>,
        "jingle.wu" <jingle.wu@....com.tw>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Wolfram Sang <wsa@...nel.org>,
        "open list:I2C SUBSYSTEM HOST DRIVERS" <linux-i2c@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 07/13] i2c: acpi: Use ACPI wake capability bit to set wake_irq

On Tue, Sep 20, 2022 at 6:32 AM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> On Mon, Sep 19, 2022 at 09:59:09AM -0600, Raul E Rangel wrote:
> > Device tree already has a mechanism to pass the wake_irq. It does this
> > by looking for the wakeup-source property and setting the
> > I2C_CLIENT_WAKE flag. This CL adds the ACPI equivalent. It uses the
> > ACPI interrupt wake flag to determine if the interrupt can be used to
> > wake the system. Previously the i2c drivers had to make assumptions and
> > blindly enable the wake IRQ. This can cause spurious wake events. e.g.,
> > If there is a device with an Active Low interrupt and the device gets
> > powered off while suspending, the interrupt line will go low since it's
> > no longer powered and wakes the system. For this reason we should
> > respect the board designers wishes and honor the wake bit defined on the
> > interrupt.
>
> ...
>
> > +     if (irq_ctx.irq == -ENOENT)
> > +             irq_ctx.irq = acpi_dev_gpio_irq_wake_get(adev, 0, &irq_ctx.wake_capable);
>
> I just realized, that there is an inconsistency on how we fill the wake_capable
> parameter. In some cases we check for IRQ for an error condition (IRQ not found)
> and in some the wake_capable still be filled.
>
> Here the best approach I believe is to add
>
>         if (irq_ctx.irq < 0)
>                 return irq_ctx.irq;
>
> I.o.w. we apply the rule "do not fill the output parameters when it's known
> to be an error condition".
>
> > +     if (wake_capable)
> > +             *wake_capable = irq_ctx.wake_capable;
>
> > +     return irq_ctx.irq;
>

I applied the following:
diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
index ba64e505183595..1618f5619d5ed9 100644
--- a/drivers/i2c/i2c-core-acpi.c
+++ b/drivers/i2c/i2c-core-acpi.c
@@ -220,7 +220,7 @@ int i2c_acpi_get_irq(struct i2c_client *client,
bool *wake_capable)
        if (irq_ctx.irq == -ENOENT)
                irq_ctx.irq = acpi_dev_gpio_irq_wake_get(adev, 0,
&irq_ctx.wake_capable);

-       if (wake_capable)
+       if (irq_ctx.irq > 0 && wake_capable)
                *wake_capable = irq_ctx.wake_capable;

        return irq_ctx.irq;

Thanks!