On Wed, Oct 30, 2013 at 2:34 AM, Lan Tianyu <tianyu.lan@xxxxxxxxx> wrote: > On 2013年10月29日 01:32, Bjorn Helgaas wrote: >> >> 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. > > > Yes, my concern is for the IO resource case of _TTP=0 and _TRA !=0. The > only reason for this case I think of is that the IO resource offsets on > the prime bus and second bus are different. In this case, we still need > to pass _TRA to new_space() and the finial resource->start still should be > acpi_resource->min + offset returned by add_io_space(), right? No, I don't think so. If the "phys_base" argument to new_space() is non-zero, it is the base of an MMIO region that needs to be ioremapped. This is handling the _TTP=1 case, where the MMIO region is translated by the bridge into an IO region on PCI. If _TTP=0, the region is IO on both the upstream and downstream sides of the host bridge, and we don't want to ioremap a new MMIO region for it. It might be part of the "legacy I/O port space," but that's already covered elsewhere. I don't think we need to add special handling for the _TTP=0 and _TRA != 0 case because I don't think it exists in the field. If and when it *does* exist, we'll know what to do. In the meantime, it should look just like the MEM path. > If yes, I think _TRA can't be applied to IO resource in the > acpi_dev_resource_address_space() regardless of the value of _TTP. > > BTW, Translation Sparse(_TRS) is only meaningful if _TTP is set.(Table > 6-185). The add_io_space() doesn't check _TTP when set sparse. So this > should be corrected? Sure, I'm OK with this. It's possible we could trip over a BIOS bug where _TRS=1 but _TTP=0, but I think the risk is low because only large ia64 boxes would use this, and there aren't very many of those. 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
