2009/12/21 Lukáš Turek <8an@xxxxxxxxxxx>: > On 21.12.2009 11:41 海藻敬之 wrote: >> In ath5k_hw_write_ofdm_timings(), comment says >> "ALGO: coef = (5 * clock * carrier_freq) / 2) ", >> but current code is >> "coef_scaled = ((5 * (clock << 24)) / 2) / channel->center_freq;" >> >> Did they match each other ? >> I am wondering the the comment is wrong, but I am not sure that either >> is wrong. > Good point, it seems the comment is wrong. The calculation would overflow > 32-bit integer if there was a multiplication instead of a division. > > Lukas Turek The original comment was: /* * ALGO -> coef = 1e8/fcarrier*fclock/40; * scaled coef to provide precision for this floating calculation */ coef_scaled = clockMhzScaled / chan->channel; So dividing by the carrier frequency sounds like the right thing, I guess the comment is wrong. I reviewed the patch, looks fine to me. The ATH hal uses a lookup table to keep it inline but I don't think we have a convenient index available to do the same. I'll see what I can find about the pilot tracking to see if that makes sense here. -- Bob Copeland %% www.bobcopeland.com -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
