ehci: diagnostics + hardening for the port-not-enabled case

Second OptiPlex QR: the Host System Error is gone (the 64-bit QH/qTD layout
fix worked), but the SETUP qTD now halts with TBYTES=0, C_ERR=3 and no
XactErr/Babble/DBE -- a split transaction with no valid response.  PORTSC
shows CCS=1, PP=1 but PED=0, i.e. the port never enabled, so the split has no
TT to address.  On Intel PCH a healthy USB2 port shows the rate-matching hub
as high-speed (PED=1), so the next step is to see every port's state.

- settle 100 ms after powering ports and clear stale change bits before the
  reset walk (RMHs come up slower than direct devices)
- retry the port reset once after settling
- log a clear line when a connected port remains disabled
- retry a failed full-speed device as low-speed (the PORTSC speed field is
  only valid once the port is enabled)
- persistent bottom-row summary: controller count, caps64, USB legacy handoff
  result, every connected port's PORTSC and the HID device count.  A hardware
  run without serial now reports the whole picture instead of one QR.

1 files changed, 35 insertions, 0 deletions

diff --git a/DEBUG_NOTES.md b/DEBUG_NOTES.md
index cd2b9ae..c9efdc1 100644
--- a/DEBUG_NOTES.md
+++ b/DEBUG_NOTES.md
@@ -664,3 +664,38 @@ hardware exposed this.
 tail): HID qTD at QH+0x80; control qTDs at +0x100/+0x140/+0x180 and the setup
 packet at +0x1C0.  The failure QR now prints `c64=` and the DMA bases
 (async/xfer/setup/buf) so the next run is self-describing.
+
+### OptiPlex 7010 — second hardware QR (after the 64-bit layout fix)
+
+```
+EHCI fail stage=1 t=20ms sp=0 dev=0 in=true len=18 c64=1
+cmd=00000021 sts=00008003
+prtsc0=0x00001005 hp=0x00003000
+qh1=48084000 qh2=40800000 nqtd=012081c0
+setup=00080e42 data=80120d80 stat=80008c80
+dma a=01208000 x=01208080 s=01208240 b=0120b000
+```
+
+- `sts=0x8003`: USBINT|USBERRINT|ASS — **no HSE**, the 64-bit QH/qTD layout is
+  fixed and the controller runs.
+- `stage=1`: the **SETUP qTD halted**, `setup=0x00080e42` -> TBYTES 0,
+  Halted, C_ERR still 3, no XactErr/Babble/DBE (a split that got no valid
+  response).
+- `prtsc0=0x1005`: device connected + powered, **PED=0** (port never
+  enabled), speed field reads full-speed.
+
+On Intel PCH the USB2 physical ports sit behind the integrated Rate Matching
+Hub, so a healthy root port shows the hub as a **high-speed** device
+(`PED=1`).  PED=0 with a connected device means the port did not enable, and
+a full/low-speed split has no valid TT to talk to -> SETUP halts.
+
+Follow-up hardening in the driver:
+- 100 ms power-up settle (RMHs are slow) and stale port-change bits cleared
+  before the reset walk
+- one reset retry after a settle
+- explicit log line when a connected port stays disabled
+- low-speed retry for a failed full-speed device (the PORTSC speed field is
+  only trustworthy once the port is enabled)
+- persistent bottom-row summary: per controller `64b=`/`leg=` handoff result,
+  every connected port's PORTSC, and the HID device count — hardware runs
+  without serial now show the whole picture, not just the first QR