linux-kernel - Re: [PATCH] Fix floppy hibernation

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Message-Id: <20090602232502.b05302d3.akpm@linux-foundation.org>
Date:	Tue, 2 Jun 2009 23:25:02 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Ondrej Zary <linux@...nbow-software.org>
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu, rjw@...k.pl
Subject: Re: [PATCH] Fix floppy hibernation

On Wed, 3 Jun 2009 08:13:26 +0200 Ondrej Zary <linux@...nbow-software.org> wrote:

> > > +static int floppy_resume(struct platform_device *dev)
> > > +{
> > > +	int fdc;
> > > +
> > > +	for (fdc = 0; fdc < N_FDC; fdc++)
> > > +		if (FDCS->address != -1)
> > > +			user_reset_fdc(-1, FD_RESET_ALWAYS, 0);
> > > +
> > > +	return 0;
> > > +}
> >
> > The patch changes the driver so that it calls user_reset_fdc() for each
> > device at resume-time.
> >
> > Why?  What effect does this have on the hardware and why does it fix
> > things?
> 
> I don't know at all, it's complete guesswork. The first thing I tested was 
> rmmod floppy && modprobe floppy after resume - it worked. Narrowing the 
> initialization code down resulted in this patch.

lol, OK.  I added this to the changelog:

  This fix resets the floppy controller on resume.  It was
  experimentally determined to bring the controller back to life - we
  don't really know why it works.

  floppy_init() does the same thing at boot/modprobe time.

Let's see how it goes...  If someone reports breakage then we can
always change the driver so that activation of your new code requires a
module parameter.
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