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

[Patrick Mochel]

On Fri, 24 Sep 2004, Zhu, Yi wrote:

> Choice 1. In 2.5 kernel, there used to be a ->save_state method in the
> device PM interface. From the "not yet updated" document
> (Documentation/power/pci.txt), this function can be used as "a notification
> that it(the device) may be entering a sleep state in the near future". If we
> take back this interface, the problem can be solved. That is, the driver
> loads firmware into memory in ->save_state and frees the memory in ->resume.
> The deadlock is resolved without any runtime memory wasted.
>
> patch embeded at the end of the mail.

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..

Thanks,


	Pat
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