Re: [PATCH V2] cfg80211: adapt to new channelization of the 6GHz band

[Arend Van Spriel <arend.vanspriel@broadcom.com>]

On May 29, 2020 11:53:30 AM Johannes Berg <johannes@sipsolutions.net> wrote:

> On Fri, 2020-05-29 at 11:41 +0200, Arend Van Spriel wrote:
>> It also fixes a missing MHZ_TO_KHZ() macro for 6GHz channels while at it.
>
> Yeah, I actually saw and fixed that earlier, but whatever. I can fix up
> any issues.
>
>> case NL80211_BAND_6GHZ:
>> - /* see 802.11ax D4.1 27.3.22.2 */
>> + /* see 802.11ax D6.1 27.3.23.2 */
>> + if (chan == 2)
>> + return MHZ_TO_KHZ(5935);
>> if (chan <= 253)
>> - return 5940 + chan * 5;
>> + return MHZ_TO_KHZ(5950 + chan * 5);
>
> So this can return 5950+5*253 == 7215
>
>> @@ -119,11 +121,14 @@ int ieee80211_freq_khz_to_channel(u32 freq)
>
>> else if (freq <= 45000) /* DMG band lower limit */
>> - /* see 802.11ax D4.1 27.3.22.2 */
>> - return (freq - 5940) / 5;
>> + /* see 802.11ax D6.1 27.3.23.2 */
>> + return (freq - 5950) / 5;
>
> and here you have no real upper bound, which is fine
>
>> @@ -1662,6 +1667,40 @@ bool ieee80211_chandef_to_operating_class(struct
>
>> + /* 6GHz, channels 1..233 */
>> + if (freq == 5935) {
>> + if (chandef->width != NL80211_CHAN_WIDTH_20)
>> + return false;
>> +
>> + *op_class = 136;
>> + return true;
>> + } else if (freq > 5935 && freq <= 7115) {
>
> but here both the comment and the code say 7115? Should that be 1..253
> and 7215, respectively?
>
> I can fix, no need to resend.

The 802.11 spec specifies the 1..253 range. The FCC has proposed the U-NII 
bands 5 to 8 for the 6G band. U-NII-8 ends at 7125 so the highest 20MHz 
center freq is 7115, ie. channel 233. Have to admit that mixing the two in 
this patch can be confusing. I leave it at your discretion how to fix it. I 
can also resend if necessary.

Regards,
Arend