linux-kernel - Re: [PATCH] PCMCIA: prevent auto insert during resume.

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Message-ID: <20071026171857.GC19019@enneenne.com>
Date:	Fri, 26 Oct 2007 19:18:57 +0200
From:	Rodolfo Giometti <giometti@...eenne.com>
To:	linux-pcmcia@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCMCIA: prevent auto insert during resume.

On Fri, Oct 26, 2007 at 06:00:31PM +0100, Russell King wrote:

> > > > Also if you didn't eject the socket, at resume the device will be
> > > > powered up again, my patch just prevents that a pre-powered off device
> > > > to be turned on at resume time.
> > > > 
> > > > However you should consider that some embedded systems have fixed
> > > > PCMCIA devices that can't be removed so there are no reasons to detect
> > > > them after resume, nobody can change them. :)
> > > > 
> > > > Also battery powered devices can go very frequently to sleep and the
> > > > current behavior force the user to switch off the unused device each
> > > > time the system resumes from sleep.
> > > 
> > > I realise that.  I do work on embedded devices, and this behaviour is
> > > explicitly there to support embedded devices.
> > > 
> > > I've suggested a workable solution to you which allows both of us to
> > > have the behaviour we both desire from the system.  That sounds like
> > > a negotiated solution to me...
> > 
> > Do you mean to switch off the socket from userland? It could be a
> > solution but in this case the device is powered on each time even if
> > for a short delay...
> 
> If it's a permanent device, and you've powered it down via pccardctl,
> then you've powered it down from userland.  So record that it's been
> powered down from userland.  Then, on resume, if it's been powered down
> from userland, don't try to re-power it on resume.

But the userland doesn't re-power it on resume... it's the kernel
itself whos re-powers the device on resume. So the userland can only
power down the device again.

Sorry for not understanding your point of view. :'(

> > Maybe we can add an entry into sysfs? Or just a module parameter? So
> > developers can choose their preferred behaviour. :)
> 
> Or that - probably a sysfs attribute on the pcmcia socket would be
> better.

Ok, but how can I do it? Can you please suggest to me the name of such
attribute and where should I add it into the PCMCIA code? Also, which
should be the default dehaviour? ;)

Thanks in advance,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail:    giometti@...eenne.com
Linux Device Driver                             giometti@...dd.com
Embedded Systems                     		giometti@...ux.it
UNIX programming                     phone:     +39 349 2432127
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