Re: pci_set_power_state() failure and breaking suspend

On Tuesday, 24 October 2006 08:54, Benjamin Herrenschmidt wrote:

So I noticed a small regression that I think might uncover a deeper
issue...

Recently, ohci1394 grew some "proper" error handling in its suspend
function, something that looks like:

        err = pci_set_power_state(pdev, pci_choose_state(pdev, state));
        if (err)
                goto out;

First, it breaks some old PowerBooks where the internal OHCI had PM
feature exposed on PCI (the pmac specific code that follows those lines
is enough on those machines).

That can easily be fixed by removing the if (err) goto out; statement
and having the pmac code set err to 0 in certain conditions, and I'll be
happy to submit a patch for this.

However, this raises the question of do we actually want to prevent
machines to suspend when they have a PCI device that don't have the PCI
PM capability ? I'm asking that because I can easily imagine that sort
of construct growing into more drivers (sounds logical if you don't
think) and I can even imagine somebody thinking it's a good idea to slap
a __must_check on pci_set_power_state() ... 

As far as the suspend to RAM is concerned, I don't know.

For the suspend to disk we can ignore the error if we know that the device
in question won't do anything like a DMA transfer into memory while we're
creating the suspend image.

Greetings,
Rafael


-- 
You never change things by fighting the existing reality.
		R. Buckminster Fuller