Only PCI was treated as a "less specific" bus that should not be
assigned if USB was already assigned, so non-PCI USB controllers
(under platform/DT or ACPI) would have all their devices *not*
treated as USB at all, resulting in external peripherals being
treated as internal ones on DT platforms.
Clarify these assignments into specificity/nesting groups instead
of having some arbitrary "X must be before Y" comments.
Fixes a4381cae8b.
xHCI host controller may register two (or more?) USB root hubs for USB
2.0 and USB 3.0, and devices under the hubs may have same ID_PATH.
So, to avoid the conflict, let's introduce ID_PATH_WITH_USB_REVISION
that includes the USB revision.
Closes#19406.
Add the i2c subsystem to those that create by-path links.
i2c devices may not have IDs so we can't rely on the by-id links
but they (or some of them) should at least have a path that we can use.
This change is only about the source tree. We have tmpfiles.d/, modprobe.d/,
sysctl.d/, and sysusers.d/, but for historical reasons, rules/ didn't fit this
pattern. We also *install* it as rules.d/. Let's rename to be consistent.
Val Packett