#705: Atheros Sensitivity
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Reporter: [EMAIL PROTECTED] | Owner:
Type: defect | Status: new
Priority: major | Milestone: version 1.0.0 - first stable
release
Component: madwifi: HAL | Version: trunk
Resolution: | Keywords:
Patch_attached: 0 |
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Comment (by [EMAIL PROTECTED]):
After more endless testing with DadWifi-openhal, DadWifi and MadWifi I
finally figured out what is actually causing the sensitivity issues.
First, my findings in my previous post on 07/23/7 are not correct. The
reason why DadWifi worked in my case and MadWifi didn't was caused by the
fact that I tested DadWifi under station mode and MadWifi under adhoc
mode. So the mode setting has influence on the sensitivity and not the
driver version.
Secondly, the HAL does cause the sensitivity issues. After testing all
possible modes under MadWifi I figured out that the sensitivity problem
always occur except when using station (client) mode. When checking the
HAL function calls made from MadWifi I found out that the ath_hal_reset
function passes the current mode setting to the HAL and influences the
sensitivity. When I override the mode argument with station mode
(HAL_M_STA) in the function calls to ath_hal_reset even when MadWifi runs
in another mode (e.g. adhoc) the sensitivity problems are gone! So the HAL
is causing these issues.
After discussing these findings with Sam Leffler I received a few hints on
the usage of ANI (ambient noise immunity) in the HAL. This algorithm can
be influenced or even turned off by using capability calls. After some
experimenting I figured out that turning off ANI after a reset in non-
station mode the sensitivity issues do not occur. So the ANI algorithm
doesn't seem to function properly in non-station modes.
I'll attach a patch that turns off ANI after each reset so please test if
it helps in your situation when having sensitivity issues. This only works
in access point/adhoc/monitor modes! If you use MadWifi as client only
this patch won't fix your sensitivity problems! ANI should work properly
in that case and any sensititivy issues are probably caused by other
(unknown) factors.
Now the bad news about this patch. First, it is a hack. The correct fix
should be applied in the HAL itself. ANI should be used on all modes, not
only in station mode to account for ambient noise and temperature changes.
This fix can only be performed by the HAL maintainer Sam Leffler. He knows
about it and was going to look at it someday but I have no idea when he's
going to look into it and when an updated version of the HAL becomes
available. Until that time this patch can be a replacement fix.
Secondly, this patch only works on older HALs. The last working HAL
version is 0.9.18.0, used in MadWifi 0.9.3.3. The newer HAL 0.9.30.13 used
in the trunk and MadWifi-dfs branch does NOT react on this patch and ANI
stays on and causes sensitivity problems. This is really a pity because I
would rather use the new HAL with better DFS support and lots of other
fixes. As long as Sam doesn't release an update of 0.9.30.13 you can
expect sensitivity issues in trunk or MadWifi-dfs.
--
Ticket URL: <http://madwifi.org/ticket/705#comment:19>
madwifi.org <http://madwifi.org/>
Multiband Atheros Driver for Wireless Fidelity
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