Re: [PATCH] PCI: Add pci shutdown ability

From: Alan Stern
Date: Tue Apr 26 2005 - 10:18:06 EST

On Tue, 26 Apr 2005, Benjamin Herrenschmidt wrote:

> The problem is, as far as I understand what David told me a while ago,
> some USB chips simply _cannot_ disable DMA without actually suspending
> the bus, which itself is a complex process that takes some time and can
> involve all sort of problems with devices / drivers that don't deal with
> suspended busses properly. I suspect other kind of chips may be
> similarily busted by design.

That's correct. However, during shutdown we don't really need to take the
time and we don't care about problems with drivers not handling suspended
buses properly. (USB devices, at least, _can_ handle such things -- it's
part of the spec.)

Alan Stern

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