madwifi.org
Tue, 06 Nov 2007 01:59:32 -0800
#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 ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Madwifi-tickets mailing list Madwifi-tickets@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/madwifi-tickets