[RESEND PATCH 1/5] platform/x86: bitland-mifs-wmi: validate WMAA status, never abort suspend

["孙 誉铭" <wolf109909@outlook.com>]

The WMAA firmware method signals "unknown/unsupported function" with
the status word 0xe000 in the reply. The driver never checked it, so
calls to functions a given firmware revision does not implement
silently returned zero-filled data instead of failing.

Worse, the platform_profile suspend hook propagated such errors: on
firmware whose perf-mode query returns values laptop_profile_get()
cannot map (e.g. MIFS v2 firmware reporting raw QFAN codes, seen on
Xiaomi Book Pro 14 2026 and REDMI Book Pro 14 2025), every suspend
attempt died with:

  dpm_run_callback(): bitland_mifs_wmi_suspend returns -22
  PM: Some devices failed to suspend, or early wake event detected

Return -EOPNOTSUPP when the firmware reports the error status word,
and make the suspend/resume hooks fault-tolerant: skip saving and
restoring the profile when the query fails instead of aborting the
whole system sleep.

Status word semantics verified against the laptop's SSDT WMAA method
(SGER=0x8000 on success, 0xe000 in the Default branch).

Signed-off-by: Yuming Sun <wolf109909@outlook.com>
---
 drivers/platform/x86/bitland-mifs-wmi.c | 31 +++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/drivers/platform/x86/bitland-mifs-wmi.c b/drivers/platform/x86/bitland-mifs-wmi.c
index 3a373184..12426d11 100644
--- a/drivers/platform/x86/bitland-mifs-wmi.c
+++ b/drivers/platform/x86/bitland-mifs-wmi.c
@@ -129,6 +129,18 @@ struct bitland_mifs_output {
 	u8 data[28];
 } __packed;
 
+/*
+ * The status word of a WMAA reply is formed by the first two bytes
+ * (reserved1 | operation << 8). MIFS firmware signals "unknown or
+ * unsupported function" with 0xe000 and success with 0x8000.
+ */
+#define MIFS_STATUS_ERROR	0xe000
+
+static u16 mifs_status(const struct bitland_mifs_output *out)
+{
+	return out->reserved1 | (out->operation << 8);
+}
+
 struct bitland_mifs_event {
 	u8 event_type;
 	u8 event_id;
@@ -159,6 +171,7 @@ struct bitland_mifs_wmi_data {
 	struct device *hwmon_dev;
 	struct device *pp_dev;
 	enum platform_profile_option saved_profile;
+	bool profile_valid;
 };
 
 static int bitland_mifs_wmi_call(struct bitland_mifs_wmi_data *data,
@@ -181,6 +194,9 @@ static int bitland_mifs_wmi_call(struct bitland_mifs_wmi_data *data,
 	memcpy(output, out_buf.data, sizeof(*output));
 	kfree(out_buf.data);
 
+	if (mifs_status(output) == MIFS_STATUS_ERROR)
+		return -EOPNOTSUPP;
+
 	return 0;
 }
 
@@ -298,17 +314,21 @@ static int bitland_mifs_wmi_suspend(struct device *dev)
 {
 	struct bitland_mifs_wmi_data *data = dev_get_drvdata(dev);
 	enum platform_profile_option profile;
-	int ret;
 
 	/* Skip event device */
 	if (!data->pp_dev)
 		return 0;
 
-	ret = laptop_profile_get(data->pp_dev, &profile);
-	if (ret == 0)
+	/*
+	 * Never abort suspend: some firmware revisions answer the perf-mode
+	 * query with values this driver cannot map, or fail the call
+	 * entirely while the system is going down.
+	 */
+	data->profile_valid = laptop_profile_get(data->pp_dev, &profile) == 0;
+	if (data->profile_valid)
 		data->saved_profile = profile;
 
-	return ret;
+	return 0;
 }
 
 static int bitland_mifs_wmi_resume(struct device *dev)
@@ -319,6 +339,9 @@ static int bitland_mifs_wmi_resume(struct device *dev)
 	if (!data->pp_dev)
 		return 0;
 
+	if (!data->profile_valid)
+		return 0;
+
 	dev_dbg(dev, "Resuming, restoring profile %d\n", data->saved_profile);
 	return laptop_profile_set(dev, data->saved_profile);
 }
-- 
2.55.0