On 2013年10月31日 00:23, Bjorn Helgaas wrote: > 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. OK. I get it. acpi_dev_resource_address_space() will only apply _TRA to resource ->start and ->end for both mem and io resource when _TTP=0. In the add_window(), the offset returned by add_io_space() will be added directly to ->start and ->end. add_window() { ... if (resource->flags & IORESOURCE_MEM) { root = &iomem_resource; offset = addr.translation_offset; } else if (resource->flags & IORESOURCE_IO) { root = &ioport_resource; offset = add_io_space(info, &addr); if (offset == ~0) return AE_OK; resource->start += offset; resource->end += offset; } else return AE_OK; ... } > >> 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. > Ok. I will add a check for _TTP before setting sparse. Something likes this. add_io_space() { ... if (addr->info.io.translation == ACPI_TYPE_TRANSLATION && addr->info.io.translation_type == ACPI_SPARSE_TRANSLATION) sparse = 1; ... } > Bjorn > -- Best regards Tianyu Lan -- 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