Re: [Xen-devel] S3 resume issues

[Malcolm Crossley <malcolm.crossley@xxxxxxxxxx>]

On 15/01/13 18:22, Ben Guthro wrote:
> On Tue, Jan 15, 2013 at 1:17 PM, Malcolm Crossley
> <malcolm.crossley@xxxxxxxxxx> wrote:
> > You get 0xFF when there is nothing responding to the ioport. If the 16550 is
> > on a PCI card then it could be the PCI connection has not been setup again
> > after the resume and you can't get to that ioport range.
> This is not a PCI card, it is on onboard card (io base 0x3f8)
>
> Ben
Interesting, it may be the serial device requires some ACPI method to be 
called to initialise/enable it correctly.
A serial port on a HP Elitebook 8570p we have seems to not initialise 
the serial port after the BIOS has started. The serial only starts 
working when the Linux kernel runs the ACPI enable method (halfway 
through the kernel boot) . I've tried to decompile the ACPI AML and it 
looks like it's enabling the serial via a microcontroller.
It could be you have a similar microcontroller based serial port on your 
system which can only be initialised via ACPI.
It might be worth checking that the io decode windows are enabled on the 
panther point chipset for the 0x3f8 port ranges. Check that bits 0-2 are 
0 at address 0x80 and that bit 0 is 0 at address 0x82 in PCI device 0:1f 
config space.
Malcolm



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