From 0b9832b712d6767d6c7b01965fd788d1ca84fc92 Mon Sep 17 00:00:00 2001
From: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Date: Mon, 13 Nov 2017 09:50:47 +0200
Subject: [PATCH] iwlwifi: mvm: don't use transmit queue hang detection when it is not possible
Git-commit: 0b9832b712d6767d6c7b01965fd788d1ca84fc92
Patch-mainline: v4.15-rc3
References: bsc#1071648

When we act as an AP, new firmware versions handle
internally the power saving clients and the driver doesn't
know that the peers went to sleep. It is, hence, possible
that a peer goes to sleep for a long time and stop pulling
frames. This will cause its transmit queue to hang which is
a condition that triggers the recovery flow in the driver.

While this client is certainly buggy (it should have pulled
the frame based on the TIM IE in the beacon), we can't blow
up because of a buggy client.

Change the current implementation to not enable the
transmit queue hang detection on queues that serve peers
when we act as an AP / GO.

We can still enable this mechanism using the debug
configuration which can come in handy when we want to
debug why the client doesn't wake up.

Cc: stable@vger.kernel.org # v4.13
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/net/wireless/intel/iwlwifi/mvm/utils.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

--- a/drivers/net/wireless/intel/iwlwifi/mvm/utils.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/utils.c
@@ -1143,9 +1143,18 @@ unsigned int iwl_mvm_get_wd_timeout(stru
 	unsigned int default_timeout =
 		cmd_q ? IWL_DEF_WD_TIMEOUT : mvm->cfg->base_params->wd_timeout;
 
-	if (!iwl_fw_dbg_trigger_enabled(mvm->fw, FW_DBG_TRIGGER_TXQ_TIMERS))
+	if (!iwl_fw_dbg_trigger_enabled(mvm->fw, FW_DBG_TRIGGER_TXQ_TIMERS)) {
+		/*
+		 * We can't know when the station is asleep or awake, so we
+		 * must disable the queue hang detection.
+		 */
+		if (fw_has_capa(&mvm->fw->ucode_capa,
+				IWL_UCODE_TLV_CAPA_STA_PM_NOTIF) &&
+		    vif && vif->type == NL80211_IFTYPE_AP)
+			return IWL_WATCHDOG_DISABLED;
 		return iwlmvm_mod_params.tfd_q_hang_detect ?
 			default_timeout : IWL_WATCHDOG_DISABLED;
+	}
 
 	trigger = iwl_fw_dbg_get_trigger(mvm->fw, FW_DBG_TRIGGER_TXQ_TIMERS);
 	txq_timer = (void *)trigger->data;