WLAN status update

Andy Green andy at openmoko.com
Mon Jan 12 09:44:33 CET 2009

Hash: SHA1

Somebody in the thread at some point said:
| Andy Green wrote:
|> maxperf is one of those names that makes you wonder why it isn't the
|> default.
| Alas, maximum performance also means maximum power burn:
| 				System battery current (*)
| AR6k module disabled:		135.2mA
| AR6k with default settings:	139.2mA
| wmiconfig --power maxperf:	260.7mA
| (*) At 4.0V lab supply. USB current limit set to 100mA.
| Oh, and I just noticed that wmiconfig --wlan disable is affected
| by --power maxperf. So to properly cool down, we also need to
| --power rec.

It seems like it is turning off ieee80211 powersaving mode (the AP
beacon dropbox system) in order to have that kind of impact.

I guess it means reported problems can be to do with the AR6001 or the
AP firmware in powersaving mode.

|> | I thought --power was mainly affecting latency, so I didn't expect
|> It sounds more like it impacts TX RF power level.
| That may at least be part of it, yes. But it looks more like a
| whole group of things. I hope Atheros can clarify.
|> It's like an on / off switch Werner.
|> Surely it doesn't have that many complicated decisions to ponder and
|> discuss :?)
| Well, you've seen the discussion on linux-wireless. The issue is
| precisely that what we have is not the simple on/off switch rfkill
| expects to find but more like a Rube Goldberg apparatus.
|> | clear that most issues are connected to the frozen access point list.
|> | I can reproduce this problem, even if it sometimes takes a while.

I don't think rfkill itself has much expectation except to stop the
transmission action.  It doesn't care how we're doing that or what
residual power is pulled at DC.  So the plan would be collect a set of
IOCTLs from shell that stop transmission and send the thing to a low
power mode additionally, and do the guts of those IOCTLs for rfkill

|> What does pulling and re-inserting the modules do for this issue?
| It resets the whole WLAN subsystem, so it clears the stuck list.
| So do suspend/resume or unbind/bind. This means that we have a
| number of work-arounds if it should turn out that the frozen list
| is some firmware feature we can't solve.
| However, I'd rather avoid this sort of work-around where you either

Sure it's a hack.  But, it is simple to explain to a user with the issue
in the meanwhile.

- -Andy
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