linux-kernel - Re: [PATCH v11 2/4] PM / Domains: add setter for dev.pm

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Date:	Fri, 08 Jan 2016 01:20:08 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc:	Daniel Kurtz <djkurtz@...omium.org>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Russell King <linux@....linux.org.uk>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Tony Lindgren <tony@...mide.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Kevin Hilman <khilman@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	dri-devel <dri-devel@...ts.freedesktop.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Pavel Machek <pavel@....cz>,
	Tomas Winkler <tomas.winkler@...el.com>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>, Len Brown <lenb@...nel.org>
Subject: Re: [PATCH v11 2/4] PM / Domains: add setter for dev.pm_domain

On Thursday, January 07, 2016 03:47:01 PM Tomeu Vizoso wrote:
> On 10 November 2015 at 10:33, Daniel Kurtz <djkurtz@...omium.org> wrote:
> [snip]
> >
> > The problem appears to be that:
> >   * On boot, platform_drv_probe() calls dev_pm_domain_attach() before
> > drv->probe(); thus, it calls dev_pm_domain_attach() while the device
> > is unbound.
> >
> >  * However, for a platform_device, the reboot path calls
> > device_shutdown(), but not __device_release_driver():
> > device_shutdown()
> >   dev->driver->shutdown => platform_drv_shutdown()
> >     dev_pm_domain_detach()
> >        dev->pm_domain->detach() => genpd_dev_pm_detach()
> >          pm_genpd_remove_device()
> >             dev_pm_domain_set(dev, NULL);
> >
> > So, for a platform_device in a genpd power domain with .shutdown
> > installed, platform_drv_shutdown() calls dev_pm_domain_detach() while
> > the device is still bound, which triggers the WARN().
> 
> Hi Rafael, Alan and Ulf,
> 
> do you have any suggestion about this? I don't really understand why
> the device is detached from the domain on shutdown.

Well, this looks like a bug to me.

Thanks,
Rafael