[Trac #852] iwconfig signal and noise level -2 dBm returned on first use

[Zarro Boogs per Child]

#852: iwconfig signal and noise level -2 dBm returned on first use
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 Reporter:  Quozl     |        Owner:  marcelo 
     Type:  defect    |       Status:  assigned
 Priority:  high      |    Milestone:  BTest-3 
Component:  wireless  |   Resolution:          
 Keywords:            |  
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Changes (by marcelo):

 * cc: rchokshi at marvell.com, javier at cozybit.com (added)
  * milestone:  Untriaged => BTest-3

Comment:

 Ronak,

 This is a firmware/hardware problem. GET_RSSI command returns, in certain
 situations (100% certain just after association happened), a value of "2"
 for absolute noise floor, while absolute SNR correctly contains "0".

 As Quozl mentions, repeated use gives realistic values.

 The following situation is common:

 {{{
 GET_RSSI, absNF = 2
 GET_RSSI, absNF = 2
 GET_RSSI, absNF = realistic value
 GET_RSSI, absNF = 2
 GET_RSSI, absNF = realistic value
 GET_RSSI, absNF = realistic value
 ...
 }}}

 Why would the firmware/hardware return noise floor = 2? Its smells like a
 default of some sort in the sensing logic?

-- 
Ticket URL: <http://dev.laptop.org/ticket/852#comment:4>
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