[PATCH v2] wifi: ath10k: Stop unanswered temperature reads

[Filippo Falezza <effeffe99@gmail.com>]

Reading the ath10k hwmon temperature sends WMI_PDEV_GET_TEMPERATURE and
waits up to 5 s (ATH10K_THERMAL_SYNC_TIMEOUT_HZ) for the reply event,
holding conf_mutex. Not all firmware answers: the WCN3990 firmware
WLAN.HL.3.3.1-00694-QCAHLSWMTPLZ-1 on a Motorola Moto G 5G Plus
codename nairo (SM7250) never sends the event, so every read of
temp1_input stalls for 5 s, logs

  ath10k_snoc 18800000.wifi: failed to synchronize thermal read

and returns -ETIMEDOUT. Tools that read all hwmon sensors, such as
lm-sensors, hang for 5 s on every run, and configuration changes of the
interface wait for conf_mutex in the meantime.

Whether the firmware answers cannot be told from the chip: firmware that
answers and firmware that does not both advertise
WMI_SERVICE_THERM_THROT, and WCN3990 firmware differs between devices.
Instead, remember that the running firmware did not answer, and return
-EOPNOTSUPP right away on later reads. Forget it when the firmware
starts, so that a restarted or updated firmware is asked again.

The first read after each firmware start still takes 5 s when the
firmware does not answer. Reads on firmware that answers are unchanged.

This change was written with the help of an AI coding assistant; see
the notes below.

Fixes: e98199a8c27f ("ath10k: enable QCA6174/QCA9377 to read the chip temperature")
Signed-off-by: Filippo Falezza <effeffe99@gmail.com>
---
Hello there,

this is v2 of the fix for ath10k temperature reads that stall for 5 s
on firmware that never answers the request, as on the WCN3990 firmware
of a Motorola Moto G 5G Plus (SM7250).

The only change from v1 is the name of the flag: it is now
ath10k_thermal.broken, as Loic suggested, instead of
temperature_unanswered. The behaviour is the same, so the testing from
v1 still applies: on the phone, the first read after the firmware
starts times out once after 5 s, every later read returns -EOPNOTSUPP
within milliseconds, and a full `sensors` run takes 25 ms instead of
5 s or more. Restarting Wi-Fi makes the driver ask the firmware again.
I have not tested firmware that answers the request.

v2 builds with W=1 for arm64 and is checkpatch --strict clean, on top
of ath-next (cd026e68fdbf).

As with v1, I wrote this with the help of an AI coding assistant
(Claude Code); the testing is on the phone.

Thanks,
Filippo
---
Changes in v2:
- Rename temperature_unanswered to broken, as suggested by Loic Poulain.
- Link to v1: https://patch.msgid.link/20261026-ath10k-temperature-v1-1-e5cd6fde7f1e@gmail.com
---
 drivers/net/wireless/ath/ath10k/core.c    | 1 +
 drivers/net/wireless/ath/ath10k/thermal.c | 9 ++++++++-
 drivers/net/wireless/ath/ath10k/thermal.h | 2 ++
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath10k/core.c b/drivers/net/wireless/ath/ath10k/core.c
index 7c2939cbde5f..a749ae582b0a 100644
--- a/drivers/net/wireless/ath/ath10k/core.c
+++ b/drivers/net/wireless/ath/ath10k/core.c
@@ -2985,6 +2985,7 @@ int ath10k_core_start(struct ath10k *ar, enum ath10k_firmware_mode mode,
 	clear_bit(ATH10K_FLAG_CRASH_FLUSH, &ar->dev_flags);
 
 	ar->running_fw = fw;
+	ar->thermal.broken = false;
 
 	if (!test_bit(ATH10K_FW_FEATURE_NON_BMI,
 		      ar->running_fw->fw_file.fw_features)) {
diff --git a/drivers/net/wireless/ath/ath10k/thermal.c b/drivers/net/wireless/ath/ath10k/thermal.c
index 9bb486f8e920..9ff7de0abd12 100644
--- a/drivers/net/wireless/ath/ath10k/thermal.c
+++ b/drivers/net/wireless/ath/ath10k/thermal.c
@@ -75,6 +75,12 @@ static ssize_t ath10k_thermal_show_temp(struct device *dev,
 		goto out;
 	}
 
+	/* Don't stall every read on firmware that never answers */
+	if (ar->thermal.broken) {
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
+
 	reinit_completion(&ar->thermal.wmi_sync);
 	ret = ath10k_wmi_pdev_get_temperature(ar);
 	if (ret) {
@@ -90,7 +96,8 @@ static ssize_t ath10k_thermal_show_temp(struct device *dev,
 	time_left = wait_for_completion_timeout(&ar->thermal.wmi_sync,
 						ATH10K_THERMAL_SYNC_TIMEOUT_HZ);
 	if (!time_left) {
-		ath10k_warn(ar, "failed to synchronize thermal read\n");
+		ath10k_warn(ar, "failed to synchronize thermal read, not asking again until the firmware restarts\n");
+		ar->thermal.broken = true;
 		ret = -ETIMEDOUT;
 		goto out;
 	}
diff --git a/drivers/net/wireless/ath/ath10k/thermal.h b/drivers/net/wireless/ath/ath10k/thermal.h
index 1f4de9fbf2b3..d1fb5b958c37 100644
--- a/drivers/net/wireless/ath/ath10k/thermal.h
+++ b/drivers/net/wireless/ath/ath10k/thermal.h
@@ -19,6 +19,8 @@ struct ath10k_thermal {
 	/* protected by conf_mutex */
 	u32 throttle_state;
 	u32 quiet_period;
+	/* the running firmware did not answer a temperature request */
+	bool broken;
 	/* temperature value in Celsius degree
 	 * protected by data_lock
 	 */

---
base-commit: cd026e68fdbf88b9cc522b76c7a9d92c9a41f709
change-id: 20261022-ath10k-temperature-22b119fd615c

Best regards,
--  
Filippo Falezza <effeffe99@gmail.com>