linux-kernel - Re: [PATCH v2 3/8] core: platform: wakeup the parent before trying any driver operations

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Message-ID: <20150526132814.GA12719@kuha.fi.intel.com>
Date:	Tue, 26 May 2015 16:28:14 +0300
From:	Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	linux-acpi@...r.kernel.org, linux-pm@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Vinod Koul <vinod.koul@...el.com>,
	Lee Jones <lee.jones@...aro.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org,
	Jarkko Nikula <jarkko.nikula@...ux.intel.com>
Subject: Re: [PATCH v2 3/8] core: platform: wakeup the parent before trying
 any driver operations

On Mon, May 25, 2015 at 01:36:43PM -0400, Alan Stern wrote:
> On Mon, 25 May 2015, Andy Shevchenko wrote:
> 
> > From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> > 
> > If the parent is still suspended when a driver probe,
> > remove or shutdown is attempted, the result may be a
> > failure.
> > 
> > For example, if the parent is a PCI MFD device that has been
> > suspended when we try to probe our device, any register
> > reads will return 0xffffffff.
> > 
> > To fix the problem, making sure the parent is always awake
> > before using driver probe, remove or shutdown.
> > 
> > Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > ---
> >  drivers/base/platform.c | 21 ++++++++++++++++++++-
> 
> Why make the changes here rather than in dd.c?  Is there something 
> special about platform devices?

There isn't. That would definitely be better.


Thanks Alan,

-- 
heikki
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