linux-kernel - [PATCH] wifi: iwlwifi: mvm: enable thermal zone only when firmware is loaded

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Date:   Mon, 10 Jul 2023 10:47:04 +0000
From:   Harry Austen <hpausten@...tonmail.com>
To:     linux-wireless@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Gregory Greenman <gregory.greenman@...el.com>,
        Kalle Valo <kvalo@...nel.org>,
        Johannes Berg <johannes.berg@...el.com>,
        Miri Korenblit <miriam.rachel.korenblit@...el.com>,
        Avraham Stern <avraham.stern@...el.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Harry Austen <hpausten@...tonmail.com>
Subject: [PATCH] wifi: iwlwifi: mvm: enable thermal zone only when firmware is loaded

In iwl_mvm_thermal_zone_register(), when registering a thermal zone, the
thermal subsystem will evaluate its temperature.
But iwl_mvm_tzone_get_temp() fails at this time because
iwl_mvm_firmware_running() returns false.
And that's why many users report that they see
"thermal thermal_zoneX: failed to read out thermal zone (-61)"
message during wifi driver probing.

This patch attempts to fix this by delaying enabling of the thermal zone
until after the firmware has been loaded/initialized. It also gets
disabled when going into suspend.

Signed-off-by: Harry Austen <hpausten@...tonmail.com>
---
 .../net/wireless/intel/iwlwifi/mvm/mac80211.c  | 18 ++++++++++++++++++
 drivers/net/wireless/intel/iwlwifi/mvm/tt.c    |  9 +--------
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c b/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c
index ce7905faa08f..a47d29a64dd4 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c
@@ -1187,6 +1187,17 @@ int iwl_mvm_mac_start(struct ieee80211_hw *hw)

 	mutex_unlock(&mvm->mutex);

+#ifdef CONFIG_THERMAL
+	/* Needs to be done outside of mutex guarded section to prevent deadlock, since enabling
+	 * the thermal zone calls the .get_temp() callback, which attempts to acquire the mutex.
+	 */
+	if (!ret) {
+		ret = thermal_zone_device_enable(mvm->tz_device.tzone);
+		if (ret)
+			IWL_DEBUG_TEMP(mvm, "Failed to enable thermal zone (err = %d)\n", ret);
+	}
+#endif
+
 	iwl_mvm_mei_set_sw_rfkill_state(mvm);

 	return ret;
@@ -1282,6 +1293,7 @@ void __iwl_mvm_mac_stop(struct iwl_mvm *mvm)
 void iwl_mvm_mac_stop(struct ieee80211_hw *hw)
 {
 	struct iwl_mvm *mvm = IWL_MAC80211_GET_MVM(hw);
+	int ret;

 	flush_work(&mvm->async_handlers_wk);
 	flush_work(&mvm->add_stream_wk);
@@ -1307,6 +1319,12 @@ void iwl_mvm_mac_stop(struct ieee80211_hw *hw)

 	iwl_mvm_mei_set_sw_rfkill_state(mvm);

+#ifdef CONFIG_THERMAL
+	ret = thermal_zone_device_disable(mvm->tz_device.tzone);
+	if (ret)
+		IWL_DEBUG_TEMP(mvm, "Failed to disable thermal zone (err = %d)\n", ret);
+#endif
+
 	mutex_lock(&mvm->mutex);
 	__iwl_mvm_mac_stop(mvm);
 	mutex_unlock(&mvm->mutex);
diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/tt.c b/drivers/net/wireless/intel/iwlwifi/mvm/tt.c
index 157e96fa23c1..964d2d011c6b 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/tt.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/tt.c
@@ -680,7 +680,7 @@ static  struct thermal_zone_device_ops tzone_ops = {

 static void iwl_mvm_thermal_zone_register(struct iwl_mvm *mvm)
 {
-	int i, ret;
+	int i;
 	char name[16];
 	static atomic_t counter = ATOMIC_INIT(0);

@@ -707,13 +707,6 @@ static void iwl_mvm_thermal_zone_register(struct iwl_mvm *mvm)
 		return;
 	}

-	ret = thermal_zone_device_enable(mvm->tz_device.tzone);
-	if (ret) {
-		IWL_DEBUG_TEMP(mvm, "Failed to enable thermal zone\n");
-		thermal_zone_device_unregister(mvm->tz_device.tzone);
-		return;
-	}
-
 	/* 0 is a valid temperature,
 	 * so initialize the array with S16_MIN which invalid temperature
 	 */
--
2.41.0