[PATCH 0/5] platform/x86: bitland-mifs-wmi: MIFS v2 firmware support (Xiaomi Book Pro 14 2026)

From: Yuming Sun <[email protected]>

This series makes the Bitland MIFS WMI driver work on the Xiaomi Book
Pro 14 2026 (Intel Panther Lake, Ultra 5 358H) and very likely on the
REDMI Book Pro 14 2025, whose suspend failure was reported earlier [1].

These machines ship a reduced MIFS firmware ("v2"): the WMAA method
implements only function groups 0x0800/0x0a00/0x0c00/0x1000, reports
the performance mode as raw QFAN EC codes {2,3,4,9,10} instead of the
v1 0..3 enumeration, and exposes no WMI fan function. Additionally the
firmware never defines ECON, so \_SB.PC00.LPCB.Q_EC._STA fails and the
ACPI EC driver never binds, which kills all EC query handlers
(including the lid switch notifications _Q0C/_Q0D).

Symptoms fixed by this series, all reproduced and verified on the
affected machine:

* Suspend/hibernate aborted with -EINVAL from the driver's suspend
  hook (same failure as [1]: "dpm_run_callback():
  bitland_mifs_wmi_suspend returns -22"; 242 failures counted in
  suspend_stats). Patch 1 makes the WMI call validate the firmware
  status word and the suspend/resume hooks fault-tolerant.

* power-profiles-daemon could not read or set the platform profile
  ("Failed to get profile for handler bitland-mifs-wmi"; selecting
  "performance" failed outright and wedged the daemon). Patch 2
  detects the v2 firmware variant at probe and maps the QFAN codes
  (2=quiet, 3=balanced, 4=speed, 9/10=extreme).

* The hwmon device reported zero RPM on all channels because the v2
  firmware has no WMI fan function. Patch 3 reads the two fan
  tachometers (u16 RPM, 0 = stopped) from the EC shared-memory window
  at 0xFE0B0300 (DSDT region "ERAM", offsets 0x69/0x6B).

* Closing the lid produced no SW_LID event (screen stayed on, keys
  pressed by the closed lid typed into the visible lock screen,
  locking the account). Patch 4 polls the LSTE lid bit in the EC
  window and, on a change, evaluates the very AML methods the EC
  query would have run (_Q0C/_Q0D), restoring proper lid events.
  DMI-gated to the affected model.

All values were reverse-engineered from the machine's DSDT/SSDT
(WMID device, _UID "MIFS") and verified live: mode switching changes
the EC QFAN register as expected, fan tachs ramp 0 -> ~2700 RPM under
load, lid close/open emit proper switch events consumed by
systemd-logind, and suspend/resume cycles complete cleanly with the
driver loaded (suspend_stats: fail 0).

Notes for reviewers:

* The v2 variant is detected at runtime (perf-mode query result
  outside the v1 enumeration) so other Bitland machines sharing this
  firmware generation get support without DMI entries; the lid quirk
  additionally requires a DMI match.
* On this platform the firmware perf-mode switch reaches Intel DTT
  (\_SB.IETM, INTC10D4) via ODV variables; mainline has no driver for
  that device, so the TDP change the firmware intends is currently
  not applied on Linux. Programming RAPL directly from this driver
  seemed inappropriate; I left it out. Happy to hear preferences.
* Interactions with the in-flight "Merge redmi-wmi into
  bitland-mifs-wmi" series [2] are limited to file context; the
  control-device paths touched here are disjoint from the event-device
  merge.

[1] https://lists.openwall.net/linux-kernel/2026/07/10/72
    "[BUG] platform/x86: bitland-mifs-wmi: Hibernation fails with
    error -22 on Xiaomi Redmi Book Pro 14 2025"
[2] https://www.spinics.net/lists/kernel/msg6309086.html
    "[PATCH v1 0/4] Merge redmi-wmi into bitland-mifs-wmi"


Yuming Sun (5):
  platform/x86: bitland-mifs-wmi: validate WMAA status, never abort
    suspend
  platform/x86: bitland-mifs-wmi: support MIFS v2 perf-mode mapping
  platform/x86: bitland-mifs-wmi: read fan tach from EC window on MIFS
    v2
  platform/x86: bitland-mifs-wmi: drive lid switch via EC poll on Xiaomi
    Book Pro 14
  Documentation: wmi: bitland-mifs-wmi: document MIFS v2 firmware
    variant

 .../wmi/devices/bitland-mifs-wmi.rst          |  26 ++
 drivers/platform/x86/bitland-mifs-wmi.c       | 272 +++++++++++++++++-
 2 files changed, 290 insertions(+), 8 deletions(-)

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2.55.0