[BUG] QWLE900V5-18 - cannot achievie 3 spatial streams link

[Michal Kazior]

On 9 December 2013 11:03, Tomasz Tajmajer <tt at elnovel.com> wrote:
>
> On 09.12.2013 10:04, Kalle Valo wrote:
>>
>> Janusz Dziedzic <janusz.dziedzic at tieto.com> writes:
>>
>>> On 6 December 2013 17:33, Tomasz Tajmajer <tt at elnovel.com> wrote:
>>>>
>>>> Hi,
>>>>
>>>> Recently, I've been making quite a lot of tests with two QWLE900V5-18
>>>> cards.
>>>> I had some issues with the drivers (e.g. regarding the regulatory
>>>> domain),
>>>> but I've managed to fix them on my own. However, there is one issue that
>>>> I
>>>> cannot deal with.
>>>> I'm trying to get the highest throughput possible using 3x3 MIMO. The
>>>> problem is that the wifi card does not set higher rates than 2x433.3Mbps
>>>> (MCS 9, VHT-NSS 2). The specification says that it should be possible to
>>>> have 3 spatial streams.
>>>> First, I thought it is a problem with some options of hostapd, but
>>>> hostapd
>>>> even does not allows me to set the [RX-STBC-12] or [RX-STBC-123]
>>>> options.
>>>> Only [RX-STBC-1] may be set in the configuration (what in fact, does not
>>>> disallows the 2x433.3Mbps link, which is another issue).
>>>> Driver info shows that the driver should support 3 spatial streams.
>>>> I am not sure where is the problem, is it some bug in hostapd, which
>>>> forces
>>>> the card to use 2 spatial streams only or is it the driver, which does
>>>> not
>>>> enable 3 streams when it is possible. The physical connectivity
>>>> (antennas
>>>> etc.) is not the problem AFAIK.
>>>>
>>> When sta assoc to ap you will get dbg mesg (you can enable this eg.
>>> when loading ath10k_core module with param - debug_mask).
>>> "mac ht peer %pM mcs cnt %d nss %d\n" - nss is interesting here
>>
>> This debug message is enabled with ATH10K_DBG_MAC. More info here:
>>
>> http://wireless.kernel.org/en/users/Drivers/ath10k/debug
>>
>>> Also rx_mcs_set for STA from ath10k_peer_assoc_h_vht() could be
>>> interesting - unfortunetly we don't print this. But you can print
>>> this.
>>
>> Indeed, we should include that to the message as well.
>>
>
> I've enabled dbg messages and added rx_mcs_set and tx_mcs_set as you
> suggested.
> Here is the output for STA:
>
> [ 2278.320312] ath10k: htt target version 2.1
> [ 2278.320455] ath10k: mac vdev create 0 (add interface) type 2 subtype 0
> [ 2278.320741] ath10k: mac vdev 0 cts_prot 0
> [ 2278.320765] ath10k: mac vdev 0 slot_time 1
> [ 2278.320801] ath10k: mac vdev 0 preamble 1n
> [ 2278.321320] ath10k: mac config channel 5180 mhz
> [ 2278.321353] ath10k: mac vdev 0 psmode disable
> [ 2278.321448] IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready
> [ 2278.321458] ath10k: mac vdev 0 psmode disable
> [ 2282.499925] wlan1: authenticate with 04:f0:21:0c:a2:3a
> [ 2282.499946] ath10k: mac config channel 5180 mhz
> [ 2282.499962] ath10k: mac vdev 0 beacon_interval 100
> [ 2282.499968] ath10k: mac vdev 0 create peer 04:f0:21:0c:a2:3a
> [ 2282.500109] ath10k: mac vdev 0 start 04:f0:21:0c:a2:3a
> [ 2282.500115] ath10k: mac vdev 0 start center_freq 5180 phymode 11ac-vht80
> [ 2282.506711] wlan1: direct probe to 04:f0:21:0c:a2:3a (try 1/3)
> [ 2282.708052] wlan1: send auth to 04:f0:21:0c:a2:3a (try 2/3)
> [ 2282.709096] wlan1: authenticated
> [ 2282.712122] wlan1: associate with 04:f0:21:0c:a2:3a (try 1/3)
> [ 2282.713907] wlan1: RX AssocResp from 04:f0:21:0c:a2:3a (capab=0x1
> status=0 aid=1)
> [ 2282.714331] ath10k: mac vdev 0 dtim_period 2
> [ 2282.714367] ath10k: mac vdev 0 slot_time 2
> [ 2282.714415] ath10k: mac ht peer 04:f0:21:0c:a2:3a mcs cnt 24 nss 3
> [ 2282.714421] ath10k: mac vht peer 04:f0:21:0c:a2:3a max_mpdu 65535 flags
> 0x601b001 rx_mcs_set 0000ffea tx_mcs_set 0000ffea
> [ 2282.714427] ath10k: mac peer 04:f0:21:0c:a2:3a phymode 11ac-vht80
> [ 2282.714435] ath10k: mac vdev 0 up (associated) bssid 04:f0:21:0c:a2:3a
> aid 1
> [ 2282.714822] ath10k: mac vdev 0 psmode enable
> [ 2282.714869] wlan1: associated
>
> And for AP:
> [ 9460.458700] ath10k: htt target version 2.1
> [ 9460.458874] ath10k: mac vdev create 0 (add interface) type 1 subtype 0
> [ 9460.459120] ath10k: mac vdev 0 cts_prot 0
> [ 9460.459155] ath10k: mac vdev 0 slot_time 1
> [ 9460.459156] ath10k: mac vdev 0 preamble 1n
> [ 9460.459385] ath10k: mac config channel 5180 mhz
> [ 9460.459434] IPv6: ADDRCONF(NETDEV_UP): wlan2: link is not ready
> [ 9461.562262] ath10k: mac vdev 0 rts threshold -1
> [ 9461.562292] ath10k: mac vdev 0 fragmentation threshold -1
> [ 9461.564900] ath10k: mac config channel 5180 mhz
> [ 9461.564919] ath10k: mac vdev 0 beacon_interval 100
> [ 9461.564923] ath10k: vdev 0 set beacon tx mode to staggered
> [ 9461.564931] ath10k: mac vdev 0 start center_freq 5180 phymode 11ac-vht80
> [ 9461.571970] ath10k: mac vdev 0 up
> [ 9461.572108] ath10k: mac vdev 0 cts_prot 0
> [ 9461.572117] ath10k: mac vdev 0 slot_time 2
> [ 9461.572241] IPv6: ADDRCONF(NETDEV_CHANGE): wlan2: link becomes ready
> [ 9461.572192] ath10k: mac vdev 0 preamble 1n
> [ 9549.331556] ath10k: vdev 0 set beacon tx mode to staggered
> [ 9549.331637] ath10k: mac vdev 0 cts_prot 0
> [ 9549.331644] ath10k: mac vdev 0 preamble 1n
> [ 9549.332425] ath10k: mac vdev 0 peer create 04:f0:21:0c:a2:3b (new sta)
> [ 9549.332628] ath10k: mac sta 04:f0:21:0c:a2:3b associated
> [ 9549.332637] ath10k: mac ht peer 04:f0:21:0c:a2:3b mcs cnt 24 nss 3
> [ 9549.332643] ath10k: mac vht peer 04:f0:21:0c:a2:3b max_mpdu 1048575 flags
> 0x601b001 rx_mcs_set 0000ffea tx_mcs_set 0000ffea
> [ 9549.332648] ath10k: mac peer 04:f0:21:0c:a2:3b phymode 11ac-vht80
>
>
> As you can see, the "nss" value is set to 3, but I've never observed VHT-NSS
> 3 reported by "iw DEV station dump". Also the maximum throughput for UDP
> measured by iperf was ~630Mbps, which seems to be the netto value for 2x433
> Mbps PHY throughput.

I wouldn't rely on station dump Tx/Rx stats (especially Tx stats which
are broken due to FW limitation).

You can create a monitor interface on the receiver side and run
wireshark in non-promiscuous mode and check radiotap headers to
confirm whether 3 spatial streams are used or not.


Michał