Messages in this thread | | | Date | Wed, 30 Oct 2013 16:34:04 +0800 | From | Lan Tianyu <> | Subject | Re: [Resend PATCH 5/5] IA64/PCI/ACPI: Rework PCI root bridge ACPI resource conversion |
| |
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@intel.com> 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?
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?
> > Bjorn >
-- Best regards Tianyu Lan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |