Re: [PATCH 1/3] PM: Introduce new top level suspend and hibernation callbacks (rev. 8)

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Sun, 2008-04-13 at 15:33 +0200, Rafael J. Wysocki wrote:
> + *     The PM core executes @prepare() for all devices before starting to
> + *     execute suspend callbacks for any of them, so drivers may assume all of
> + *     the other devices to be present and functional while @prepare() is being
> + *     executed.  In particular, it is safe to make GFP_KERNEL memory
> + *     allocations from within @prepare().  However, drivers may NOT assume
> + *     anything about the availability of the user space at that time and it
> + *     is not correct to request firmware from within @prepare() (it's too
> + *     late to do that).  [To work around this limitation, drivers may
> + *     register suspend and hibernation notifiers that are executed before the
> + *     freezing of tasks.]

Can you tell me why you kept that limitation with user space ?

I don't see the point... On the contrary, prepare() is the pefect place
to implement handshaking with userspace for drivers that need to do so,
such as the DRM.

Ben.