linux-kernel - Re: [PATCH RFC] gpio: pca953x: Configure wake-up path when wake-up is enabled

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]

Date:   Thu, 4 Apr 2019 17:46:14 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Geert Uytterhoeven <geert+renesas@...der.be>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Kevin Hilman <khilman@...nel.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC] gpio: pca953x: Configure wake-up path when wake-up is enabled

[...]

> > > However, while this approach is known to work fine on other boards, with
> > > other GPIO and interrupt controllers (gpio-rcar, irq-renesas-irqc,
> > > irq-renesas-intc-irqpin), it wouldn't work on Ebisu-4D, due to different
> > > device suspend ordering.
> > >
> > > The proper ordering is:
> > >   1. When gpio-keys is suspended, its suspend handler calls
> > >      enable_irq_wake(), invoking pca953x_irq_set_wake(), and causing
> > >      pca953x_chip.wakeup_path to be incremented,
> > >   2. When gpio-pca953x is suspended, it checks pca953x_chip.wakeup_path,
> > >      and marks the device to be part of the wake-up path.
> >
> > Right.
> >
> > >
> > > However, gpio-keys is suspended _after_ gpio-pca953x, breaking the
> > > scheme :-(
> >
> > Would it make sense to fixup the ordering issue via creating a
> > parent/child relationship or setting up a device link?
>
> Could that be due to gpio_keys not having rudimentary Runtime PM support?

You are saying that the parent/child relation ship is already there?

In such case, it shouldn't matter whether runtime PM is deployed or
not, the PM core should propagate the wakeup_path flag from children
to parents in __device_suspend() and in device_suspend_late(). If that
doesn't happen there is bug in the PM core.

Kind regards
Uffe