### System details

ThinkPad X1 Carbon Gen 11 (21HMCTO1WW), Intel i7-1365U, MediaTek T700 5G modem [14c3:4d75] (no SIM installed), BIOS N3XET68W (1.43), Omarchy 4.0.4-1, linux-omarchy 7.2.5-3

### What's wrong?

Once the `mtk_t7xx` WWAN driver gets into a bad state, every suspend attempt is aborted, so the laptop stays awake with the lid closed. Suspend is retried about every 30 seconds until the battery is empty.

**What happened**

- Sun 4 Oct 09:16: boot.
- Sun 4 Oct 17:16:17 (8 hours later): first failure, on a runtime suspend:
  `mtk_t7xx 0000:08:00.0: [PM] SAP suspend error: -110`
  `mtk_t7xx 0000:08:00.0: can't suspend (t7xx_pci_pm_runtime_suspend [mtk_t7xx] returned -110)`
- From then on no system suspend succeeded for the rest of the boot (3 days). Each attempt logs:

  ```
  kernel: PM: suspend entry (s2idle)
  kernel: mtk_t7xx 0000:08:00.0: [PM] SAP suspend error: -110
  kernel: mtk_t7xx 0000:08:00.0: PM: pci_pm_suspend(): t7xx_pci_pm_suspend [mtk_t7xx] returns -110
  kernel: mtk_t7xx 0000:08:00.0: PM: failed to suspend async: error -110
  kernel: PM: Some devices failed to suspend, or early wake event detected
  systemd-sleep: Failed to put system to sleep. System resumed again: Connection timed out
  systemd[1]: Failed to start System Suspend.
  ```

- 16,906 `SAP suspend error` lines in that boot; `omarchy-sleep-lock.service` restart counter reached 8454.
- Wed 7 Oct 10:21: lid closed on battery. About 118 failed suspends per hour followed.
- Wed 7 Oct 18:58: "Time to recharge! Battery is down to 6%" notification.
- Wed 7 Oct 19:43:32: journal ends mid-retry with no shutdown or hibernate sequence. The next boot was a cold boot (`PM: Image not found`).

**Expected**

The laptop suspends on lid close, or at least does not run the battery to empty when suspend cannot succeed.

**Notes**

- The modem is unused: no SIM, and `thinkpad_acpi` reports `tpacpi_wwan_sw: radio is blocked` at boot.
- The installed module already contains the latest upstream fix for this error (net-next commit ae733795e593, "net: wwan: t7xx: Add delay between MD and SAP suspend"): the `msleep(50)` is present in `__t7xx_pci_pm_suspend` in the 7.2.5-3 module. It was not enough on this machine.
- The trigger is not known. It took 8 hours of uptime to appear, so I have no quick reproduction.
- Workaround applied: `blacklist mtk_t7xx` in `/etc/modprobe.d/` and `modprobe -r mtk_t7xx`. Not yet confirmed over a suspend cycle on this machine; other distros' reports of the same error say removing the module restores suspend (Arch FS#79728, Launchpad #1990700).

**Related**

- #1556: an X1 Carbon Gen 12 comment there shows the same failure class with a different WWAN modem and driver (`mhi-pci-generic`, error -16).
- #8106: same failure class (a driver aborts every suspend, lid close never suspends) with `brcmfmac` on T2 Macs.
- #13256: no hibernate on critical battery. Hibernation is set up on this machine (`resume=` on the kernel command line) and UPower is on `CriticalPowerAction=Auto`, yet the battery ran to empty.

Filed by Claude Opus 5.5 via Claude Code.