mt76x2u: util: unlock DFS channels

[Rising-Sun]

enables DFS channels on mt76x2u devices. Tested on COMFAST CF-WU782AC.

Credit goes to Lorenzo Bianconi
modification of b9f3193

Signed-off-by: Yushi Nishida kyro2man@gmx.net

[LorenzoBianconi]

@Rising-Sun have you tested if the device is able to detect radar pulses? AFAIK the hw should not be able to do so

[Rising-Sun]

@LorenzoBianconi LorenzoBianconi
okay. will test if it detects a radar pulse. Till yet no radar pulses at my place on ch 120 (116), comparing against a mt7612e adapter.
Now added a fritzbox for radar detection comparison.

[nicklowe]

I would suggest this needs testing with something like https://github.com/adriangranados/dfs-pulse-tester and a HackRF One,

If it does not detect, this should not be merged.

[morrownr]

The lack of DFS support in this and the mt76x10u drivers is putting adapters based on these chipsets at a competitive disadvantage. The latest out-of-kernel Realtek driver for their 8812au chipset does support DFS channels and it works well.

I'd be willing to help make this happen if I can. The cost of a HackRF One is a little steep but there has got to be a way to make this happen.

Regards

[RichardoC]

@Rising-Sun is it worth opening this change request with the upstream Linux kernel? It seems likely one of those maintainers might be able to test this.

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/wireless/mediatek/mt76/mt76x02_util.c?h=v6.2-rc1#n85 is the relevant line there

[joopdo]

This seems to have been merged to master. (https://github.com/openwrt/mt76/blob/master/mt76x02_util.c line 72)

[RichardoC]

This seems to have been merged to master. (https://github.com/openwrt/mt76/blob/master/mt76x02_util.c line 72)

That's for mt76x02 rather than mt76x02u (note the u suffix)
That confused me too!

[lriesebos]

this seems to be a pretty old PR by now. was this already solved in another way, or is this still pending?

[morrownr]

@lriesebos

I think AP mode on DFS channels requires an additional FCC cert that Mediatek does not have for usb chips. That is my theory. I really wish we could see a change. I think is more important to sales than Mediatek management understands.