[RFC] ACPI vs device ordering on resume

[Stephen Hemminger <shemminger@osdl.org>]

If I do a suspend-to-ram then resume on a Sony Vaio laptop with sky2 driver,
the first interrupt gets misrouted to the original shared IRQ, rather than
to the MSI irq expected.

During the pci_restore process, the MSI information and the PCI command register 
are restored properly. But later during resume, inside the ACPI evaluation of
the WAK method, the PCI_COMMAND  INTX_DISABLE (0x400) flag is being cleared.
My guess is that the BIOS ends up doing some resetting of devices.

I may be able to workaround the problem for this one device, but it brings up
a more general issue about what the ordering should be during resume. If ACPI
evaluation (which I assume talks to the BIOS), might change device state, it
seems that ACPI code should execute before resuming devices not after. But changing
the order here seems drastic.

An alternate solution would be to have two pm_ops, one for early_resume
and another for late, and split the ACPI work.

--- 2.6.19-rc5.orig/kernel/power/main.c	2006-11-14 14:24:37.000000000 -0800
+++ 2.6.19-rc5/kernel/power/main.c	2006-11-14 14:25:23.000000000 -0800
@@ -132,12 +132,12 @@
 
 static void suspend_finish(suspend_state_t state)
 {
+	if (pm_ops && pm_ops->finish)
+		pm_ops->finish(state);
 	device_resume();
 	resume_console();
 	thaw_processes();
 	enable_nonboot_cpus();
-	if (pm_ops && pm_ops->finish)
-		pm_ops->finish(state);
 	pm_restore_console();
 }
 


-- 
Stephen Hemminger <shemminger@osdl.org>