linux-kernel - Re: [linux-sunxi] [PATCH v2 8/9] power: supply: axp20x_usb

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Date:   Sun, 5 Jan 2020 18:47:47 +0800
From:   Chen-Yu Tsai <wens@...e.org>
To:     Samuel Holland <samuel@...lland.org>
Cc:     Sebastian Reichel <sre@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Oskari Lemmela <oskari@...mela.net>,
        "open list:THERMAL" <linux-pm@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-sunxi <linux-sunxi@...glegroups.com>
Subject: Re: [linux-sunxi] [PATCH v2 8/9] power: supply: axp20x_usb_power: Add
 wakeup control

On Sun, Jan 5, 2020 at 9:24 AM Samuel Holland <samuel@...lland.org> wrote:
>
> The USB power supply input can be used as a wakeup source. Hook up the
> VBUS_PLUGIN IRQ to trigger wakeup based on userspace configuration.
>
> To do this, we must remember the list of IRQs for the life of the
> device. To know how much space to allocate for the flexible array
> member, we switch from using a NULL sentinel to using an array length.
>
> Because we now depend on the specific order of the IRQs (we assume
> VBUS_PLUGIN is first and always present), failing to acquire an IRQ
> during probe must be a fatal error.
>
> To avoid spuriously waking up the system when the USB power supply is
> not configured as a wakeup source, we must explicitly disable all non-
> wake IRQs during system suspend. This is because the SoC's NMI input is
> shared among all IRQs on the AXP PMIC. Due to the use of regmap-irq, the
> individual IRQs within the PMIC are nested threaded interrupts, and are
> therefore not automatically disabled during system suspend.
>
> The upshot is that if any other device within the MFD (such as the power
> key) is an enabled wakeup source, all enabled IRQs within the PMIC will
> cause wakeup. We still need to call enable_irq_wake() when we *do* want
> wakeup, in case those other wakeup sources on the PMIC are all disabled.
>
> Signed-off-by: Samuel Holland <samuel@...lland.org>

Reviewed-by: Chen-Yu Tsai <wens@...e.org>