#10080 NORM Not Tri: XO-1.5: "iwlist scanning" reports no networks after some time

[Zarro Boogs per Child]

#10080: XO-1.5: "iwlist scanning" reports no networks after some time
------------------------------------+---------------------------------------
           Reporter:  sascha_silbe  |       Owner:  dsaxena      
               Type:  defect        |      Status:  new          
           Priority:  normal        |   Milestone:  Not Triaged  
          Component:  kernel        |     Version:  not specified
         Resolution:                |    Keywords:  libertas     
        Next_action:  diagnose      |    Verified:  0            
Deployment_affected:                |   Blockedby:               
           Blocking:                |  
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Comment(by Quozl):

 As non-root user the ''iwlist'' command will only provide left-over scan
 results from a previous scan.  These scan results are kept for about 15
 seconds after a previous scan, after which the response is "No scan
 results".

 An actual scan causes wireless LED to flash.  Fetching previous scan
 results does not cause the wireless LED to flash.

 As root user the ''iwlist'' command clears the current scan results, scans
 for new results, and then returns them.  If during this time another
 process asks for last scan results, the return is delayed until the scan
 in progress completes.

 A similar symptom reproduced on os114 with ''Automatic power management''
 enabled.  Does not occur if there is no suspend.

 If Network Manager is stopped then the symptom changes.  This is
 presumably because Network Manager performs scans.

 Consider the following commands:

 {{{
 /etc/init.d/NetworkManager stop
 iwlist eth0 scan
 }}}

 The enter key is not pressed after the last line above, and the laptop is
 allowed to idle suspend.  When enter is pressed, the laptop wakes,
 ''iwlist'' runs, and reports ''Interface doesn't support scanning''.

 If this test is repeated with a "sleep 1" preceeding the ''iwlist''
 command, ''iwlist'' reports ''Interface doesn't support scanning : Network
 is down'', which implies that the interface goes through some automated
 transition shortly after resume.

 If this test is further changed to:

 {{{
 sleep 1 ; ifconfig eth0 up ; iwlist eth0 scan
 }}}

 Then the scan completes normally.

 If this test is further changed to:

 {{{
 sleep 1 ; ifconfig eth0 up ; iwlist eth0 scan last
 }}}

 Then we see ''No scan results'', showing that the resume cleared the scan
 result set.

 Lastly, if the test is:
 {{{
 sleep 1 ; \
 ifconfig eth0 up ; \
 iwlist eth0 scan ; \
 sleep 16 ; \
 iwlist eth0 scan last
 }}}

 Then the final output is also "No scan results".  (The laptop needs to be
 kept awake during those 16 seconds using touchpad or keyboard.)

 Sugar continues to show scan results on the Neighbourhood View despite "No
 scan results" being shown by ''iwlist''.  The access points remain
 selectable and association is successful.

 In summary, I don't see a problem with this behaviour, and I can't see
 what needs fixing.

-- 
Ticket URL: <http://dev.laptop.org/ticket/10080#comment:1>
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