Re: suspend/resume support for driver requires an external firmware

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

> We talked about this in Ottawa a few months ago, and I think this is the
> right approach. Note though, that I think it needs to be more complete:
> 
> - There needs to be restore_state() to be symmetic.
> - There needs to be the proper failure recovery
>   If save_state() or suspend() fails, every device that has had their
>   state saved needs to be restored.
> - It needs to be called for all power management requests.
> - The PCI implementation should call pci_save_state() in it, instead of in
>   ->suspend().
> 
> It would be great if you could add these things. Otherwise, I'll add it to
> my TODO list..

Additionally, for devices like the above that need either to rely on
userland for firmware download or to allocate large amounts of memory
for firmware backup/restore, I think we need to revive the pre-suspend
and post-resume notifiers ... Of course, if a device that needs userland
to reload a firmware is on the swap patch, then we have a chicken & egg
problem, but there is no easy solution for that one, unless the driver
uses the pre-suspend callback to pre-load the firmware that it will need
for resume

Ben.