Date: Thu, 13 Jan 2011 22:05:13 +0530
From: Rajkumar Manoharan <rmanoharan@atheros.com>
To: Felix Fietkau <nbd@openwrt.org>
CC: Rajkumar Manoharan <Rajkumar.Manoharan@Atheros.com>,
	=?iso-8859-1?Q?Bj=F6rn?= Smedman <bjorn.smedman@venatech.se>,
	"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: Re: [RFC] ath9k: Handle interface changes properly
Message-ID: <20110113163513.GA9291@vmraj-lnx.users.atheros.com>
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On Thu, Jan 13, 2011 at 07:53:27PM +0530, Felix Fietkau wrote:
> On 2011-01-13 6:18 AM, Rajkumar Manoharan wrote:
> > On Thu, Jan 13, 2011 at 01:21:47AM +0530, Felix Fietkau wrote:
> >>  On 2011-01-12 10:06 AM, Bj?rn Smedman wrote:
> >>  >  On Wed, Jan 12, 2011 at 3:30 PM, Rajkumar Manoharan
> >>  >  <rmanoharan@atheros.com>   wrote:
> >>  >>   The commit ""ath9k: Add change_interface callback" was failed
> >>  >>   to update of hw opmode, ani and interrupt mask. This leads
> >>  >>   to break p2p functionality on ath9k. And the existing add and
> >>  >>   remove interface functions are not handling hw opmode and
> >>  >>   ANI properly.
> >>  >>
> >>  >>   This patch combines the common code in interface callbacks
> >>  >>   and also takes care of multi-vif cases.
> >>  >
> >>  >  How does your patch handle the race condition between the interface
> >>  >  change done in process context and the beacon tasklet triggered by
> >>  >  SWBA?
> >>  >
> >>  >  Also, perhaps more applicable to the commit log than the patch, how
> >>  >  can opmode be properly handled in multi-vif cases? I mean let's say I
> >>  >  have two AP vifs and then change one into STA, is the opmode then STA?
> >>  >  Compare that to the case where I have two STA vifs and change one into
> >>  >  AP; so again I have one AP and one STA vif but this time opmode is AP,
> >>  >  right? I can see how I can be wrong about these examples but I can't
> >>  >  really see how the opmode concept can be properly handled in multi-vif
> >>  >  cases.
> >>  I think opmode should be handled as follows:
> >>  If there is at least one AP interface, opmode should be AP, regardless
> >>  of what the other interfaces are set to.
> >>  If there is no AP vif, opmode can be set to the primary vif type.
> >>
> > Correct. this RFC patch does the same.
> Really? I don't see that being handled properly, it still seems to 
> overwrite ah->opmode based on a single vif type for some types.
> Also, there is no reason to have a WDS opmode in ath9k_hw. WDS is 
> typically used along with AP mode interfaces, and where it is not, the 
> AP opmode should be used for ath9k_hw anyway.
Instead of setting opmde as AP for WDS, it is better to handle WDS
case in ath9k_hw.
> Maybe it would be a good idea to clean this up and first limit the 
> number of different types that we pass to ath9k_hw (i.e. only AP, ADHOC, 
> STA). Later we can make a separate enum for that to avoid passing the 
> type as-is entirely.
Just to stick with the currently supported interfaces list, WDS also included.
> I think the mesh point opmode has no place in ath9k_hw. Right now it is 
> treated like ad-hoc, but I think that's completely wrong. Mesh should 
> behave just like AP mode, as no ad-hoc style TSF synchronization should 
> be done by the hardware, and 802.11s mesh nodes do not compete for 
> beacon transmission.
This is a different issue and it has to be addressed in separate patch.

--
Rajkumar