On Thu, 2013-06-13 at 01:23 +0200, Rafael J. Wysocki wrote: > Hi All, > > It turns out that some BIOSes add container device IDs as _CIDs to device > object that in principle may be matched against the other scan handlers (or > ACPI drivers, but that's not a problem, because the container scan handler > can co-exist with an ACPI driver). That's why our recent fix for an issue > related to the ACPI video driver had to be reverted right before -rc5. I am familiar with this firmware, although I no longer have access to the systems. An SBA device object has _HID with an HP-specific PNPID and _CID with a generic container PNPID. The _HID allows an OS with the HP SBA driver (which recognizes the _HID) to enable the SBA's I/O TLB functionality, while the _CID allows an OS without the HP SBA driver to boot-up by treating this SBA as a container. The _CID is needed because some OS skips scanning underneath when it finds an unrecognized object. > Although I submitted an alternative fix for that bug, I think the problem > with the container scan handler possibly matching devices already having > some other scan handlers attached needs addressing, because we may need to > use the container hotplug profile for those devices. The following patch > series is supposed to address it. When the HP SBA driver is bound to the SBA object, this driver needs to handle a hotplug request when it is supported. This is because the I/O TLB functionality requires its hot-delete operation as well. The container scan handler can be used only when this driver is bound to the SBA object as a container and therefore its I/O TLB functionality is not used. > [1/5] ACPI / scan: Do not bind ACPI drivers to objects with scan handlers > (this version shouldn't break the Tony's IA64 HP box the previous one broke) > [2/5] ACPI / scan: Separate hotplug profiles from scan handlers > [3/5] ACPI / scan: Add hotplug profile pointer to struct acpi_device > [4/5] ACPI / scan: Use container hotplug profile for matching device objects > [5/5] ACPI / ia64 / sba_iommu: Use ACPI scan handler for discovery > > Patches [1-4/5] were run on my Toshiba test box and didn't break it, but it > really doesn't do any ACPI hotplug notifications. > > Patch [5/5] is kind of additional, but it wouldn't work correctly without the > previous ones (to be honest, I haven't tried to compile it yet, but here it > goes for completness). I think we only need patch [5/5] to address the problem. We have enhanced the match function of scan handlers to match a proper driver with respect to their priority order, i.e. matching with _HID first and then with _CIDs. Patch [5/5] should assure that the HP SBA driver is bound to an SBA object when this driver is configured to the kernel. Thanks, -Toshi -- 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
