A controller reaches a device by the path to it and, for a slow device,
through the hub that translates for it. Neither was described, so a
device behind a hub was addressed as though it were on the root port.
The route string is that path: each hub between the device and the root
contributes a nibble holding the port the next thing down occupies, tier
nearest the root in the lowest nibble. Walking up from the device reaches
the deepest tier first, so shifting left by a nibble each time leaves them
in the order the field wants. The walk stops after five, which is what
the field holds and what USB allows, and a port above fifteen is clamped.
Slot context dword 2 names the transaction translator carrying a low or
full speed device behind a high speed hub. It reports the hub by slot,
where EHCI reports it by USB address, and it names the nearest high speed
ancestor rather than the immediate parent, since a full speed hub below a
high speed one is itself carried by the translator above it. The think
time comes from the hub descriptor by way of the hub class driver, in the
same units.
xhci_epalloc() carried a copy of sam_ehci.c's block, writing
epinfo->hubaddr and epinfo->hubport, which is how EHCI describes a split
transaction in its queue head. This driver never read either field, and
xHCI wants the information in the slot context. Both fields and the code
setting them are removed.
Multi-TT is not set, for the reason given in the previous commit.
No functional change: hubs cannot be enabled yet, and a device on a root
port has neither hubs above it nor a translator.
Assisted-by: Claude:claude-opus-5
Signed-off-by: Justin Hammond <justin@dynam.ac>
9af6540381