Re: mt76: MT7921K monitor mode not working

[Lorenzo Bianconi <lorenzo@kernel.org>]

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> On Saturday, 4 December 2021 01:55:04 CET sean.wang@mediatek.com wrote:
> > >ack, I agree, but I guess the point here is what is the difference (from the fw pov) if you disable runtime-pm/deep-sleep before/after the vif is added. I guess it is supposed to be the same, right?
> > 
> > yes, it is supposed to be the same.
> 
> Two things which were noticed too:
> 
> First finding: If I run `iw dev mon0 del` after a non-working tcpdump dump 
> session then I get following error messages before my complete system freezes:
> 
>     [  492.812050] mt7921e 0000:04:00.0: Message 40000002 (seq 14) timeout
>     [  492.818587] mt7921e 0000:04:00.0: chip reset
>     [  495.883934] mt7921e 0000:04:00.0: Message 00000046 (seq 15) timeout
> 
> Second one: We cannot see beacons on 2.4Ghz and 5GHz when runtime-pm + deep-
> sleep is set to 0.
> 
> 
> 
> Regarding the initial problem: following works (when ignoring the missing 
> beacons for now):
> 
>     echo 0 > /sys/kernel/debug/ieee80211/phy0/mt76/runtime-pm
>     echo 0 > /sys/kernel/debug/ieee80211/phy0/mt76/deep-sleep
>     iw dev wlp4s0 del
>     iw phy0 interface add mon0 type monitor
>     ip link set up dev mon0
>     iw dev mon0 set channel 11
>     tcpdump -ni mon0
> 
> 
> What is often not working:
> 
>     iw dev wlp4s0 del
>     iw phy0 interface add mon0 type monitor
>     ip link set up dev mon0
>     iw dev mon0 set channel 11
>     tcpdump -ni mon0 &
>     sleep 10
>     echo 0 > /sys/kernel/debug/ieee80211/phy0/mt76/runtime-pm
>     sleep 5
>     echo 0 > /sys/kernel/debug/ieee80211/phy0/mt76/deep-sleep
> 
> 
> What I have seem to break sometimes (but cannot reproduce reliably):
> 
>     iw dev wlp4s0 del
>     iw phy0 interface add mon0 type monitor
>     ip link set up dev mon0
>     iw dev mon0 set channel 11
>     echo 0 > /sys/kernel/debug/ieee80211/phy0/mt76/runtime-pm
>     echo 0 > /sys/kernel/debug/ieee80211/phy0/mt76/deep-sleep
>     tcpdump -ni mon0
> 
> 
> The channel 11 is rather busy. It is for example also used for our community 
> mesh network in the city center - so is rather easy for me to see that it is 
> able to sniff traffic or not.

Hi Sven,

can you please try the patch below to see if it fixes the crash/hang in monitor
mode?

Regards,
Lorenzo

From 2502ead5ba1f580d63bbc65165acb0139dc94ed8 Mon Sep 17 00:00:00 2001
Message-Id: <2502ead5ba1f580d63bbc65165acb0139dc94ed8.1639689141.git.lorenzo@kernel.org>
From: Lorenzo Bianconi <lorenzo@kernel.org>
Date: Thu, 16 Dec 2021 20:40:16 +0100
Subject: [PATCH] mt76: mt7921: fix a possible race enabling/disabling
 runtime-pm

Fix a possible race enabling/disabling runtime-pm between mt7921_pm_set
and mt7921_poll_rx().

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c | 3 ---
 drivers/net/wireless/mediatek/mt76/mt7921/debugfs.c  | 6 ++++--
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c b/drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c
index af43bcb54578..306e9eaea917 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c
@@ -7,9 +7,6 @@ int mt76_connac_pm_wake(struct mt76_phy *phy, struct mt76_connac_pm *pm)
 {
 	struct mt76_dev *dev = phy->dev;
 
-	if (!pm->enable)
-		return 0;
-
 	if (mt76_is_usb(dev))
 		return 0;
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/debugfs.c b/drivers/net/wireless/mediatek/mt76/mt7921/debugfs.c
index 7cdfdf83529f..59b047dceca0 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/debugfs.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/debugfs.c
@@ -276,7 +276,7 @@ mt7921_pm_set(void *data, u64 val)
 	struct mt7921_dev *dev = data;
 	struct mt76_connac_pm *pm = &dev->pm;
 
-	mt7921_mutex_acquire(dev);
+	mutex_lock(&dev->mt76.mutex);
 
 	if (val == pm->enable)
 		goto out;
@@ -286,6 +286,7 @@ mt7921_pm_set(void *data, u64 val)
 		pm->stats.last_doze_event = jiffies;
 	}
 	pm->enable = val;
+	mt76_connac_pm_wake(&dev->mphy, &dev->pm);
 
 	ieee80211_iterate_active_interfaces(mt76_hw(dev),
 					    IEEE80211_IFACE_ITER_RESUME_ALL,
@@ -293,8 +294,9 @@ mt7921_pm_set(void *data, u64 val)
 
 	mt76_connac_mcu_set_deep_sleep(&dev->mt76, pm->ds_enable);
 
+	mt76_connac_power_save_sched(&dev->mphy, &dev->pm);
 out:
-	mt7921_mutex_release(dev);
+	mutex_unlock(&dev->mt76.mutex);
 
 	return 0;
 }
-- 
2.33.1


> 
> Kind regards,
> 	Sven



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