Causes for TSF never increasing ?

[jcelerier]

Hello,
I'm trying to see how I can use TSF for synchronization.

But when I try to access it whenever I get a beacon, which I parse through NL80211_ATTR_BSS, I can see all the usual parameters changing, but not TSF :

if ( tb[NL80211_BSS_SIGNAL_MBM])
	bss->signal_mbm=mnl_attr_get_u32(tb[NL80211_BSS_SIGNAL_MBM]);

if ( tb[NL80211_BSS_SEEN_MS_AGO])
	bss->seen_ms_ago = mnl_attr_get_u32(tb[NL80211_BSS_SEEN_MS_AGO]);

if (tb[NL80211_BSS_TSF])
    bss->tsf = mnl_attr_get_u64(tb[NL80211_BSS_TSF]);

fprintf(stderr, "data: %u %u %lu !\n", bss->signal_mbm, bss->seen_ms_ago, bss->tsf);

here I see signal_mbm and seen_ms_ago moving so I know I'm getting new data, but tsf stays constant for any given wifi network I try. Do some hardware just not support TSF ?