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#1 2012-09-24 23:18:46

Aghosh993
Member
Registered: 2012-09-24
Posts: 11

Intel Wireless 6250

Hi,

Recently I installed Arch Linux on my Thinkpad X220, and everything seems to be fine hardware-wise, except the fact that my WiFi card (Intel Wireless-N 6250) cannot connect at wireless-N speeds. Below is some output from "lspci -nnk":

03:00.0 Network controller [0280]: Intel Corporation Centrino Advanced-N + WiMAX 6250 [8086:0089] (rev 35)
	Subsystem: Intel Corporation Centrino Advanced-N + WiMAX 6250 2x2 ABG [8086:1316]
	Kernel driver in use: iwlwifi

"dmesg | grep iwl":

[    2.715322] iwlwifi: Intel(R) Wireless WiFi Link AGN driver for Linux, in-tree:
[    2.715325] iwlwifi: Copyright(c) 2003-2012 Intel Corporation
[    2.715404] iwlwifi 0000:03:00.0: pci_resource_len = 0x00002000
[    2.715406] iwlwifi 0000:03:00.0: pci_resource_base = ffffc90005478000
[    2.715408] iwlwifi 0000:03:00.0: HW Revision ID = 0x35
[    2.715522] iwlwifi 0000:03:00.0: irq 48 for MSI/MSI-X
[    2.772859] iwlwifi 0000:03:00.0: loaded firmware version 41.28.5.1 build 33926
[    2.773057] iwlwifi 0000:03:00.0: CONFIG_IWLWIFI_DEBUG disabled
[    2.773058] iwlwifi 0000:03:00.0: CONFIG_IWLWIFI_DEBUGFS disabled
[    2.773059] iwlwifi 0000:03:00.0: CONFIG_IWLWIFI_DEVICE_TRACING enabled
[    2.773060] iwlwifi 0000:03:00.0: CONFIG_IWLWIFI_DEVICE_TESTMODE enabled
[    2.773061] iwlwifi 0000:03:00.0: CONFIG_IWLWIFI_P2P disabled
[    2.773063] iwlwifi 0000:03:00.0: Detected Intel(R) Centrino(R) Advanced-N + WiMAX 6250 ABG, REV=0x84
[    2.773174] iwlwifi 0000:03:00.0: L1 Enabled; Disabling L0S
[    2.773354] iwlwifi 0000:03:00.0: RF_KILL bit toggled to enable radio.
[    2.784618] iwlwifi 0000:03:00.0: device EEPROM VER=0x536, CALIB=0x6
[    2.784621] iwlwifi 0000:03:00.0: Device SKU: 0x1B0
[    2.784623] iwlwifi 0000:03:00.0: Valid Tx ant: 0x3, Valid Rx ant: 0x3
[    2.784641] iwlwifi 0000:03:00.0: Tunable channels: 13 802.11bg, 24 802.11a channels
[    2.787649] ieee80211 phy0: Selected rate control algorithm 'iwl-agn-rs'
[    4.769431] iwlwifi 0000:03:00.0: L1 Enabled; Disabling L0S
[    4.769635] iwlwifi 0000:03:00.0: Radio type=0x1-0x2-0x0
[    5.012930] iwlwifi 0000:03:00.0: L1 Enabled; Disabling L0S
[    5.013153] iwlwifi 0000:03:00.0: Radio type=0x1-0x2-0x0
[   16.097058] iwlwifi 0000:03:00.0: L1 Enabled; Disabling L0S
[   16.097269] iwlwifi 0000:03:00.0: Radio type=0x1-0x2-0x0
[   16.258647] iwlwifi 0000:03:00.0: L1 Enabled; Disabling L0S
[   16.258855] iwlwifi 0000:03:00.0: Radio type=0x1-0x2-0x0
[   16.820538] iwlwifi 0000:03:00.0: L1 Enabled; Disabling L0S
[   16.820749] iwlwifi 0000:03:00.0: Radio type=0x1-0x2-0x0
[   16.965725] iwlwifi 0000:03:00.0: L1 Enabled; Disabling L0S
[   16.966020] iwlwifi 0000:03:00.0: Radio type=0x1-0x2-0x0
[   33.998756] iwlwifi 0000:03:00.0: L1 Enabled; Disabling L0S
[   33.999038] iwlwifi 0000:03:00.0: Radio type=0x1-0x2-0x0

iwconfig:

wlan0     IEEE 802.11abg  ESSID:"Poly-WiFi"  
          Mode:Managed  Frequency:5.805 GHz  Access Point: xx:xx:xx:xx:xx:xx  
          Bit Rate=48 Mb/s   Tx-Power=15 dBm   
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality=34/70  Signal level=-76 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:4  Invalid misc:118   Missed beacon:0

lshw | less:

           *-network
                description: Wireless interface
                product: Centrino Advanced-N + WiMAX 6250
                vendor: Intel Corporation
                physical id: 0
                bus info: pci@0000:03:00.0
                logical name: wlan0
                version: 35
                serial: XX:XX:XX:XX:00:10
                width: 64 bits
                clock: 33MHz
                capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
                configuration: broadcast=yes driver=iwlwifi driverversion=3.5.3-1-ARCH firmware=41.28.5.1 build 33926 ip=FFF.FFF.FFF.FFF latency=0 link=yes multicast=yes wireless=IEEE 802.11abg
                resources: irq:48 memory:f2500000-f2501fff

An interesting thing I have observed is the fact that the card is being always picked up as an "ABG" device as opposed to "ABGN." Also, 5 GHz is fully operational, as verified by iwconfig above, and connectivity is quite stable. However, I really would prefer operating at bonded (40 MHz) N speeds (or at least single-channel 130 Mbps operation), to take advantage of the fact that, well, my hardware certainly supports it, and the additional WAN bandwidth available at my university (And I am positive the network I am connecting to has wireless-N, as my friends on Mac and Windows machines can connect at N speeds perfectly fine, and I had a single-antenna/single-radio Realtek card before this that connected at 72 Mbps.)

Also, I have tried the trick of rmmod-ing and then modprobing the iwlwifi driver with 11n_disable=0 (and various other permutations). Either way, the card is stubbornly set to use 802.11g. Attempting to connect to my N-only router at home is also futile, and I have to set the router to mixed mode to get a successful connection.

Thanks in advance!

EDIT: Thought I would add the fact that to rule out mis-indication of the network mode, I have repeatedly run speed tests on our university network (during off-peak hours), and the speeds always max out at around 20 - 22 Mbps symmetric, which I believe is about the upper bound of useful transfer rates over 802.11g infrastructure (And I know for a fact that we have far more bandwidth than that... the routers should at least have 100 Mbps (probably gigabit since they are Cisco wireless-N routers) ports, and our main campus line (as tested via gigabit ethernet on my X220) is around 400 Mbps.

Last edited by Aghosh993 (2012-09-24 23:25:40)

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#2 2012-09-25 04:40:53

bwat47
Member
Registered: 2009-10-07
Posts: 637

Re: Intel Wireless 6250

Probably not very helpful, but I'll chime in to mention that my machine also has intel 6250 wireless and wireless N 40mhz works fine here, on 2.4ghz (I have a 2.4ghz only tp-link router that does support 2.4ghz with 40mhz bonding). I can generally connect with 200-300mb/s, so it definitely should be able to work with your hardware.

EDIT: Mine does appear to be a different revision though, and lists AGN instead of AGB like your lspci -nnk output is showing:

 Network controller [0280]: Intel Corporation Centrino Advanced-N + WiMAX 6250 [8086:0087] (rev 5f)
	Subsystem: Intel Corporation Centrino Advanced-N + WiMAX 6250 2x2 AGN [8086:1301]
	Kernel driver in use: iwlwifi

Last edited by bwat47 (2012-09-25 04:50:01)

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#3 2012-09-25 09:41:10

Strike0
Member
From: Germany
Registered: 2011-09-05
Posts: 1,277

Re: Intel Wireless 6250

The two cards even have different device-IDs. I would not worry about the "ABG" nomenclatura though, because they deliberately put an advanced before the N ;-)

Three things to try:

modprobe iwlwifi swcrypto=1

The "11n_disable" parameter has options "2" and "3" to try out, but it reads like you have tried those
Try how it behaves with the LTS kernel.

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#4 2012-09-25 15:57:38

teateawhy
Member
From: GER
Registered: 2012-03-05
Posts: 1,048
Website

Re: Intel Wireless 6250

Measuring speed with iwconfig seems to be a bad idea.
On my computer with  similar hardware (tpx220 + intel wifi 6205 + 5 ghz router) i get different results shortly after another.
Example:
iwconfig #1
Bit Rate=6 Mb/s   Tx-Power=15 dBm   
iwconfig #2
Bit Rate=243 Mb/s   Tx-Power=15 dBm
iwconfig #3
Bit Rate=270 Mb/s   Tx-Power=15 dBm

The bit Rate keeps changing every measurement, it is usually displayed higher after loading a web page and at 6 Mb/s when idle.

Last edited by teateawhy (2012-09-25 15:58:48)

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#5 2012-09-26 18:23:40

Aghosh993
Member
Registered: 2012-09-24
Posts: 11

Re: Intel Wireless 6250

Yeah tried the additional modprobe options... no luck. I will attempt to install the LTS Kernel when I have some additional time.
Also, I keep hearing that 11n has been disabled at a microcode/driver level since some kernel revision, due to widespread issues people were having with the rate control algorithm. Apparently, there is a patch floating around somewhere that corrects this issue and restores N capability, but I can't seem to find it... any ideas/experiences?

Thanks!
- A.G.

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#6 2012-09-29 05:30:14

Aghosh993
Member
Registered: 2012-09-24
Posts: 11

Re: Intel Wireless 6250

teateawhy wrote:

Measuring speed with iwconfig seems to be a bad idea.
On my computer with  similar hardware (tpx220 + intel wifi 6205 + 5 ghz router) i get different results shortly after another.
Example:
iwconfig #1
Bit Rate=6 Mb/s   Tx-Power=15 dBm   
iwconfig #2
Bit Rate=243 Mb/s   Tx-Power=15 dBm
iwconfig #3
Bit Rate=270 Mb/s   Tx-Power=15 dBm

The bit Rate keeps changing every measurement, it is usually displayed higher after loading a web page and at 6 Mb/s when idle.

Since you are on similar hardware, can you post your kernel version, and the output of lspci -nnk ?

Thanks!
-A.G.

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