Hi! With the wi(4) driver, is txpower output of ifconfig correct for cards which are capable of more than 100mW (20dBm) power?
In the stable OpenBSD 3.9 sources the maximum is _hardcoded_ to 20dBm. There has been only one reference (providing the code below): http://marc.theaimsgroup.com/?l=openbsd-misc&m=110841989007050&w=2 The patch posted there has already been merged. /usr/src/sys/dev/ic/if_wi.c of 3.9-stable): wi_set_txpower() { int8_t tmp; ... /* Convert dBM to internal TX power value */ if (sc->wi_txpower > 20) power = 128; else if (sc->wi_txpower < -43) power = 127; else { tmp = sc->wi_txpower; tmp = -12 - tmp; tmp <<= 2; power = (u_int16_t)tmp; } ... } and wi_get_txpower() { ... power = CSR_READ_2(sc, WI_RESP0); /* Convert internal TX power value to dBM */ if (power > 255) txpower->i_val = 255; else { tmp = power; tmp >>= 2; txpower->i_val = (u_int16_t)(-12 - tmp); } } Obviously the range [20,-43] (dBm) is mapped to an 8-bit integer using a "magic" constant of -12. This results in 128 as maximum value, 127 as lowest and 0 as the "middle" power setting, right? Btw, 20dBm also matches the IEEE80211_TXPOWER_MAX define in /usr/sys/net80211/ieee80211_var.h (set to 100 [mW]). Now, what if the maximum internal value of 128 does _not_ correspond to 100mW/20dBm? Say, if I have a 200mW capable card, is it correct to change the constant to -9 to have a mapping of [23,-40]? And what if the maximum power is 250mW or just 50mW? Always adjust the constant and recompile? So, how do I find the correct max/min values for txpower->i_val to adjust the above conversions? Perhaps in the firmware? Any references (e.g. to some driver documentation) are appreciated! Thanks, Walter
