Re: [PATCH] mt76: Enable NL80211_EXT_FEATURE_CQM_RSSI_LIST

Kristian Evensen [off-list ref] writes:

So have you tested this and with what devices? For example, does it work
with recently added USB devices?

-- 
Kalle Valo

On 8/12/2018 8:14 PM, Kalle Valo wrote:

Kristian Evensen [off-list ref] writes:

quoted

Enable the use of CQM with mt76-devices.

Signed-off-by: Kristian Evensen <redacted>
---
  drivers/net/wireless/mediatek/mt76/mac80211.c | 2 ++
  1 file changed, 2 insertions(+)

diff --git a/drivers/net/wireless/mediatek/mt76/mac80211.c b/drivers/net/wireless/mediatek/mt76/mac80211.c
index 029d54bc..3eb328ff 100644
--- a/drivers/net/wireless/mediatek/mt76/mac80211.c
+++ b/drivers/net/wireless/mediatek/mt76/mac80211.c

@@ -305,6 +305,8 @@ int mt76_register_device(struct mt76_dev *dev, bool vht,

  	wiphy->features |= NL80211_FEATURE_ACTIVE_MONITOR;

+	wiphy_ext_feature_set(wiphy, NL80211_EXT_FEATURE_CQM_RSSI_LIST);

So have you tested this and with what devices? For example, does it work
with recently added USB devices?

I was looking into this as it looks suspicious to me. From reading the 
description of this ext_feature flag it seems this is an extention of CQM:

"""
  * @NL80211_EXT_FEATURE_CQM_RSSI_LIST: With this driver the
  *	%NL80211_ATTR_CQM_RSSI_THOLD attribute accepts a list of zero or more
  *	RSSI threshold values to monitor rather than exactly one threshold.
"""

Also looking at mt76x2_bss_info_changed() it does not handle 
BSS_CHANGED_CQM so I doubt it has support for it (yet). The driver does 
not use IEEE80211_VIF_SUPPORTS_CQM_RSSI which is a requirement for it.

Regards,
Arend


https://elixir.bootlin.com/linux/latest/source/drivers/net/wireless/mediatek/mt76/mt76x2_main.c#L223

Hi Kalle & Arnd,
On Sun, Aug 12, 2018 at 8:44 PM Arend van Spriel
[off-list ref] wrote:

quoted

So have you tested this and with what devices? For example, does it work
with recently added USB devices?

I was looking into this as it looks suspicious to me. From reading the
description of this ext_feature flag it seems this is an extention of CQM:

Thank you very much for your feedback. My commit message should have
been more detailed, sorry about that. I have checked that the flag
works as intended with mt7602-, mt7603- and mt7612-based wifi cards. I
have not had the opportunity to test with any of the recently added
USB devices, as I don't have access to any of those.

In order to test the flag, I wrote a small program which subscribes to
the CQM-multicast group, passes an RSSI threshold-list to the kernel
and logs the received CQM-events. I then disconnected and connected
the wifi-antennas of the different cards. My threshold list was {-70,
-60, -50, -40} and while unscrewing the antenna I received multiple
below-events. When I attached the antenna again, I received multiple
above-events. As an example, here is the log when I tested with mt7612
(singal level when starting was ~-48 dBm):

Requested nl80211 generic netlink id
nl80211 has generic netlink id: 23
mlme ID is 5
Added socket to mlme group
Sent NL80211_CMD_SET_CQM
No error
Wifi (idx 18) went below threshold. RSSI -52
Wifi (idx 18) went above threshold. RSSI -49
Wifi (idx 18) went below threshold. RSSI -52
Wifi (idx 18) went below threshold. RSSI -62
Wifi (idx 18) went above threshold. RSSI -59
Wifi (idx 18) went above threshold. RSSI -49

Based on how I interpret the output and my understanding of how CQM +
RSSI_LIST works, this output shows that mt76 works fine with
NL80211_EXT_FEATURE_CQM_RSSI_LIST (at least for my cards). The list
was interpreted and handled correctly, as I received events when the
RSSI passed different thresholds in my list (-50, -60).

BR,
Kristian