Re: [PATCH 4/4] ath9k: improve reliability of beacon transmission and stuck beacon handling

[Felix Fietkau <nbd@openwrt.org>]

On 2011-03-10 2:04 PM, Felix Fietkau wrote:
> On 2011-03-10 10:46 AM, Vasanthakumar Thiagarajan wrote:
>> On Thu, Mar 10, 2011 at 06:05:03AM +0530, Felix Fietkau wrote:
>>> ath9k calls ath9k_hw_stoptxdma every time it sends a beacon, however there
>>> is not much point in doing that if the previous beacon and mcast traffic
>>> went out properly. On AR9380, calling that function too often can result
>>> in an increase of stuck beacons due to differences in the handling of the
>>> queue enable/disable functionality.
>>> 
>>> With this patch, the queue will only be explicitly stopped if the previous
>>> data frames were not sent successfully. With the beacon code being the
>>> only remaining user of ath9k_hw_stoptxdma, this function can be simplified
>>> in order to remove the now pointless attempts at waiting for transmission
>>> completion, which would never happen at this point due to the different
>>> method of tx scheduling of the beacon queue.
>> 
>> Thanks. Can this patch be split into two, one which possibly fixes btsuck
>> (a stable fix) and the other one which is a cleanup?.
> OK. I'll split it up, but won't propose it for stable yet, I want to see
> how well it works for users first.
Actually, now that I think about it, it can't easily be split up without
introducing potential side-effects. The unmodified ath9k_hw_stoptxdma
should not be called when a beacon is stuck, because then it will hit
the code path that tries to kill pending frames by setting various flags
and waiting for a while, which is absolutely counterproductive when
being done to the beacon queue.
I think it's better to leave the patch as a whole, the changes to
ath9k_hw_stoptxdma do not fix anything without the changes to beacon.c.

- Felix