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Ticket #2316 (new defect)

Opened 5 years ago

Last modified 5 years ago

Countrycode muddle needs to be normalized / consolidated

Reported by: tsharples Assigned to:
Priority: major Milestone:
Component: madwifi: other Version: trunk
Keywords: countrycode Cc:
Patch is attached: 0 Pending: 0

Description

In testing r4068 (hal-testing) and r4071 (trunk) we are finding fairly serious inconsistencies and silly limitations in the handling and results of countrycode arguments appended to modprobe during initial system setup (insmod ath_pci countrycode=XXX. For example, a countrycode of 843 on r4068 with a ubnt sr9 card insmods properly; the resulting iwlist ath0 scan gives:

ath0      10 channels in total; available frequencies :
          Channel 02 : 2.422 GHz
          Channel 01 : 2.422 GHz
          Channel 14 : 2.427 GHz
          Channel 12 : 2.427 GHz
          Channel 11 : 2.427 GHz
          Channel 24 : 2.432 GHz
          Channel 22 : 2.432 GHz
          Channel 21 : 2.432 GHz
          Channel 32 : 2.437 GHz
          Channel 31 : 2.437 GHz  

However on r4071 (trunk) with the same sr9 radio, insmod with countrycode 843 executes without command-line error- but wifi0 is never created. To create a usable interface we had to use countrycode 840 instead, but this won't allow us to select the half and quarter channels:

ath0      23 channels in total; available frequencies : <<-- 23 channels??
          Channel 01 : 2.412 GHz
          Channel 02 : 2.417 GHz
          Channel 03 : 2.422 GHz
          Channel 04 : 2.427 GHz
          Channel 05 : 2.432 GHz
          Channel 06 : 2.437 GHz
          Channel 07 : 2.442 GHz
          Channel 08 : 2.447 GHz
          Channel 09 : 2.452 GHz
          Channel 10 : 2.457 GHz
          Channel 11 : 2.462 GHz

Testing r4068 with a ubnt XR5 radio instead and a countrycode of 842, iwlist ath0 scan gives:

  26 channels in total; available frequencies :
          Channel 05 : 4.942 GHz
          Channel 10 : 4.945 GHz
          Channel 15 : 4.947 GHz
          Channel 20 : 4.95 GHz
          Channel 25 : 4.952 GHz
          Channel 30 : 4.955 GHz
          Channel 35 : 4.957 GHz
          Channel 40 : 4.96 GHz
          Channel 45 : 4.962 GHz
          Channel 50 : 4.965 GHz
          Channel 55 : 4.967 GHz
          Channel 60 : 4.97 GHz
          Channel 65 : 4.972 GHz
          Channel 70 : 4.975 GHz
          Channel 75 : 4.977 GHz
          Channel 80 : 4.98 GHz
          Channel 85 : 4.982 GHz
          Channel 90 : 4.985 GHz
          Channel 95 : 4.987 GHz
          Current Frequency:4.942 GHz (Channel 5)

and testing with my analyzer shows that, indeed, this card is now operating on the 4.9 Ghz band. However I'm not sure it will work very well since the XR5 has sharp filters at the edge of the 5Ghz band. On the other hand, moving the same XR5 card to the r4071 platform, and issuing the same countrycode of 842, insmod executes without errors, yet again never creates the wifi0 interface.

Other than the confusion this situation creates during testing, there's a very real operational consequence - with either branch, it appears to be impossible to build a dual-radio repeater node with one card set to e.g. 5.8 Ghz , and the other set to a fractional 900 Mhz channel. This can be a crippling limitation in e.g. an urban area obstructions on one path and with heavy interference from cell-towers requiring 900Mhz to operate on quarter channels.

If trunk is to be the mainstream flavor of madwifi, I believe it needs to allow (a) setting of half and quarter channels on an as-needed basis and (b) support for multiple radios such that the user is free to select full, half, or quarter channel operation on either or both radios without restriction, at least in the US market. The other suppliers of embedded wireless equipment such as Tranzeo, Demarctech, Lucaya, etc. all offer this capability in FCC-certified units so it must be permitted here.

Change History

(in reply to: ↑ description ) 09/28/09 00:36:20 changed by anonymous

This exactly the same issue we are trying to resolve. Since aht5k is a way out, it would be great to see the half/quarter channel options work, especially on the UBNT 900 cards.