Scanning regression since "cfg80211: use DS or HT operation IEs to determine BSS channel"
Rafał Miłecki
zajec5 at gmail.com
Tue Mar 26 13:10:37 EDT 2013
Hi,
I've just finished bisecting wireless scanning regression I'm
experiencing with my 14e4:432b (BCM4322) and b43 driver.
The problem is getting my network visible in scanning results (iw dev
wlan0 scan). I've to repeat scanning dozens of time to notice my AP.
It's also well visible when using wpa_supplicant. It takes from 20s to
100s before I get the "Trying to authenticate with".
The performance however is not affected. Once I connect to my network,
I can transmit (tested with iperf) with stable 21.5Mb/s which is just
great for 802.11g.
After going back to the kernel before that commit it takes
wpa_supplicant less than 2 seconds to connect to my WiFi network.
My network is at channel 13, I still have to verify if it matters.
Any thought about that?
The first bad commit (I've verified manually after bisecting) appears to be:
0172bb75073e11a5aa9d8a953bdaefb8709f00c8 is the first bad commit
commit 0172bb75073e11a5aa9d8a953bdaefb8709f00c8
Author: Johannes Berg <johannes.berg at intel.com>
Date: Fri Nov 23 14:23:30 2012 +0100
cfg80211: use DS or HT operation IEs to determine BSS channel
Currently, mac80211 checks the DS params IE if present and
uses it for the (primary) BSS channel, instead of the one
that the frame was received on. This is particularly useful
in the 2.4 GHz band since a frame is often received on one
of the adjacent channels due to overlap.
Move this code to cfg80211 so other drivers also do this.
Additionally, on 5 GHz, in particular with some (possibly)
upcoming changes in 802.11ai and duplicate transmissions
when wider channels are used, something similar happens.
So if present, also use the (primary) channel information
contained in the HT operation IE.
Signed-off-by: Johannes Berg <johannes.berg at intel.com>
--
Rafał
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BSS 00:11:22:33:44:55 (on wlan0)
TSF: 165376384 usec (0d, 00:02:45)
freq: 2472
beacon interval: 100
capability: ESS Privacy ShortSlotTime (0x0411)
signal: -50.00 dBm
last seen: 153 ms ago
Information elements from Probe Response frame:
SSID: zajec_poznan_160
Supported rates: 1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0
DS Parameter set: channel 13
Country: PL Environment: Indoor/Outdoor
Channels [1 - 13] @ 20 dBm
ERP: Barker_Preamble_Mode
Extended supported rates: 24.0 36.0 48.0 54.0
RSN: * Version: 1
* Group cipher: CCMP
* Pairwise ciphers: CCMP
* Authentication suites: PSK
* Capabilities: 16-PTKSA-RC (0x000c)
HT capabilities:
Capabilities: 0x104e
HT20/HT40
SM Power Save disabled
RX HT40 SGI
No RX STBC
Max AMSDU length: 3839 bytes
DSSS/CCK HT40
Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
Minimum RX AMPDU time spacing: 8 usec (0x06)
HT TX/RX MCS rate indexes supported: 0-15
HT operation:
* primary channel: 13
* secondary channel offset: below
* STA channel width: any
* RIFS: 0
* HT protection: 20 MHz
* non-GF present: 0
* OBSS non-GF present: 0
* dual beacon: 0
* dual CTS protection: 0
* STBC beacon: 0
* L-SIG TXOP Prot: 0
* PCO active: 0
* PCO phase: 0
WMM: * Parameter version 1
* BE: CW 15-1023, AIFSN 3
* BK: CW 15-1023, AIFSN 7
* VI: CW 7-15, AIFSN 2, TXOP 3008 usec
* VO: acm CW 3-7, AIFSN 2, TXOP 1504 usec
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