________________________________________ From: mcgrof@xxxxxxxxx [mcgrof@xxxxxxxxx] on behalf of Luis R. Rodriguez [mcgrof@xxxxxxxxxxxxxxxx] Sent: Thursday, December 13, 2012 2:49 PM To: Johannes Berg; Bitterli, Felix Cc: linux-wireless@xxxxxxxxxxxxxxx Subject: Re: [RFC 2/2] cfg80211: check (VHT) bandwidth against regulatory On Thu, Dec 13, 2012 at 2:47 PM, Johannes Berg <johannes@xxxxxxxxxxxxxxxx> wrote: > On Thu, 2012-12-13 at 14:38 -0800, Luis R. Rodriguez wrote: >> On Thu, Dec 6, 2012 at 8:53 AM, Johannes Berg <johannes@xxxxxxxxxxxxxxxx> wrote: >> > - /* TODO: missing regulatory check on 80/160 bandwidth */ >> > + /* >> > + * TODO: What if there are only certain 80/160/80+80 MHz channels >> > + * allowed by the driver, or only certain combinations? >> > + * For 40 MHz the driver can set the NO_HT40 flags, but for >> > + * 80/160 MHz and in particular 80+80 MHz this isn't really >> > + * feasible -- should we ask the driver here? >> > + */ >> >> It'd be real odd if a card could only do certain settings but at least >> from what I was told the spec did limit the required combinations to a >> smaller set so technically I could see the firmware having the checks >> to only allow those settings. I don't think it makes sense to add this >> as a limitation that gets annotated by a flag on the driver though. I >> suspect we can assume a driver that supports VHT80 will support those >> combos defined on the spec and so will a card that can support VHT160 >> and the only restriction really should be regulatory. > > Ok so mostly I'm thinking 80+80 limitations. I could imagine, for > example, that a card doesn't want to do 80+80 if they're adjacent (do > 160 instead), but I have no idea what 80+80 cards are like... Pfft, yeah I have no clue yet. Felix would you know if there are any limitations hardware wise in theory at least of doing 80+80 configurations (apart form what the standard would allow). Luis [Felix:] Firstly, overlapping 40M channels are not allowed, overlapping 80M channels are not allowed, same for 160M. So each individual 80 of the 80+80 has to follow previous rule. In case the two 80 are adjacent, it's called 160. Best regards, Felix (apologies for owa quoting improperly) -- 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
