Re: [ath9k-devel] ath9k: ap tsf seems random and only uses lower 24 bits or so

[Felix Fietkau <nbd@openwrt.org>]

On 2010-06-29 8:08 AM, Benoit Papillault wrote:
> Le 29/06/2010 00:55, Felix Fietkau a écrit :
>> On 2010-06-29 12:31 AM, Björn Smedman wrote:
>>> Hi all,
>>>
>>> I'm getting weird values from the debugfs file ieee80211/phy0/tsf: the
>>> value goes up and down rather randomly and only the lower 24 bits or
>>> so seem to ever be used (see below for details).
>>>
>>> The only thing running on phy0 is a single ap interface (and the
>>> monitor companion that hostapd sets up). I was expecting tsf to
>>> increase monotonically until all 64 bits had been used.
>>>
>>> For a moment I thought it might be the kernel snprintf (on mips)
>>> playing a trick on me so I tried the following patch. But the result
>>> is the same.
>> IMHO the most likely problem source is stuck beacons. Please compile the
>> driver with the debug option enabled and load it with
>> insmod ath9k debug=0x00000100
>>
>> - Felix
> 
> Humm... I observed a similar behavior a while ago because only the 15 
> lower bits of rstamp were used when being extended (but rstamp is 32 
> bits in fact). If so, it has been fixed by Felix in the following commit :
Nope, different issue. The TSF extending applies only to rx timestamps,
however Björn has been observing weird TSF values from the hw register.
The Rx TSF timestamp is pretty much irrelevant in AP mode.

- Felix