On Sat, Oct 26, 2013 at 10:53 AM, Lan Tianyu <tianyu.lan@xxxxxxxxx> wrote: > On 10/24/2013 06:39 AM, Bjorn Helgaas wrote: >> On Fri, Oct 18, 2013 at 08:44:12PM +0800, Lan Tianyu wrote: >>> >>> On 10/18/2013 04:33 AM, Bjorn Helgaas wrote: >>>> I wonder if it would make sense to make >>>> acpi_dev_resource_address_space() ignore addr.translation_offset for >>>> IO resources. Or maybe ignore it if the _TTP (type translation) bit >>>> is set? >>> >>> >>> I wonder why current code doesn't check _TTP? The code in the >>> add_io_space() seems to think _TTP is always set, right? >> >> I think it's an oversight, and you should fix it. I suggest that you >> ignore the _TRA value when _TTP is set. Obviously this only applies >> to I/O port resources, since _TTP is only defined in the I/O Resource >> Flag (Table 6-185 in ACPI 5.0 spec). > > _TTP is also defined in the Memory Resource flag, Please have a look at > Table 6-184 in the ACPI 5.0 Spec. Yes, you're right. That would be for a host bridge that converts I/O on the primary (upstream) side of the bridge to memory on the PCI side. I've never seen such a bridge, and I can't really imagine why anybody would do that. But I guess you should be able to safely ignore _TRA when _TTP is set in either a MEM or IO descriptor, because the same reasoning should apply to both. > I am not sure how to deal with _TTP unsetting io resource? _TTP unsetting > mean the resource is IO on the primary side and also IO on the secondary > side. If _TTP is not set, I guess you would apply _TRA. That's what you already do for MEM descriptors, and think you should just do the same for IO descriptors. I would guess that having _TTP = 0 and _TRA != 0 is rare for IO descriptors, but I suppose it could happen. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
