Re: [BUG] powerpc does not save msi state [was Re: [PATCH 5/7] pci: Export the pci_restore_msi_state() function

On Sat, 2007-10-20 at 16:43 +1000, Michael Ellerman wrote:

On Fri, 2007-10-19 at 17:53 -0700, David Miller wrote:

quoted

I don't see this, in all cases write_msi_msg() will transfer
the given "*msg" to entry->msg by this assignment in
drivers/pci/msi.c:

void write_msi_msg(unsigned int irq, struct msi_msg *msg)
{
 ...
	entry->msg = *msg;
}

So as long as write_msi_msg() is invoked, it will be saved
properly.

Platforms need not do this explicitly.

I'm short on context here, and it's Saturday, so excuse me if I'm
missing the point somewhere.

On pseries machines we don't call write_msi_msg(), because we don't
control the contents of the message, firmware does. So entry->msg will
be bogus.

That's a pity, but AFAIK it shouldn't be a problem because we don't
enable CONFIG_PM on those machines anyway. If we ever want to we'll need
to sort out with firmware how that will work WRT restoring MSI state.

The PCI error recovery that Linas is working on requires the MSI state
to be restored after we do PCI reset to recover from PCI errors.