Re: [PATCH] MMC: Add 400ms to CAFE SD controller resume path

From: Andrew Morton
Date: Thu May 28 2009 - 04:37:27 EST

On Fri, 22 May 2009 13:51:50 +0200 Pierre Ossman <pierre@xxxxxxxxx> wrote:

> On Wed, 13 May 2009 20:05:56 +0000
> Deepak Saxena <dsaxena@xxxxxxxxxxx> wrote:
> >
> > The CAFE SD controller takes a long time to completely resume
> > and w/o this patch, we do not redetect an existing card but
> > instead detect it as a new one. Even with MMC_UNSAFE_RESUME
> > enabled, this leads to the partition table on the device being
> > wiped out.
> >
> > See for gory details.

hm, this sounds like a fairly serious problem, but the patch is nearly
a year old.

> > Signed-off-by: Deepak Saxena <dsaxena@xxxxxxxxxx>
> >
> Reading through that report, I don't believe you properly worked around
> the bug. You only avoid bug 1339, but that's only mildly related.
> What this workaround does is to make sure that MMC_UNSAFE_RESUME
> actually works. But if you change cards during suspend, the VFS bug
> should reappear and you'll corrupt the partition table.

What do you think the VFS did wrong here?

> And as for 1339, has there been any more work done on why this problem
> doesn't appear in OFW? I'd be a lot happier if we could make things
> work without artificial delays.

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