[rt2x00-users] rt2x00: tsf_sync values?

Ivo Van Doorn ivdoorn at gmail.com
Mon Jul 5 21:15:36 AEST 2010


Hi,

> rt2x00reg.h defines the following sync modes:
>
>  63 enum tsf_sync {
>  64         TSF_SYNC_NONE = 0,
>  65         TSF_SYNC_INFRA = 1,
>  66         TSF_SYNC_BEACON = 2,
>  67 };
>
> The sync value is on all ralink devices a two bit field.
>
> On rt2800 however there is one more sync mode:
>
> 3: ap mode -> sync with nobody
>
> At the moment we just programm TSF_SYNC_BEACON = 2 to the hardware which is
> used for AdHoc beaconing setup (witch includes syncing the TSF with the TSF
> of other AdHoc nodes). Basically the beaconing works correct but I _guess_
> (and this is really just a guess) it would be possible to change the APs TSF
> counter by sending a beacon with the same SSID to it.

But what would the difference be with TSF_SYNC_NONE be?

> So, do the older ralink devices really use only values 0..2 for the
> synchronization setup?

Yes, the values are taken from the older drivers, and are valid for all devices
up to rt61pci/rt73usb. However the usage of TSF_SYNC_BEACON for AP mode
is a guess since we don't have access to Ralink drivers whcih support AP mode.

We might introduce the new TSF flag, which maps back to TSF_SYNC_BEACON
on the older drivers...

Ivo




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