Hi Alvin, On Fri, 2022-02-25 at 22:55 +0000, Alvin Šipraga wrote: > Hi James, > > James Prestwood <prestwoj@xxxxxxxxx> writes: > > > This driver does not advertise this feature yet scanning with on an > > AP interface appears to work just fine. > > --- > > drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > I've submitted this patch mainly to start a discussion about it. I > > find it hard to believe that ALL brcmfmac devices support AP > > scanning > > in which case this feature needs to be limited to those devices > > only. Trouble is there is no FW feature for AP scanning AFAIK. > > > > In any case I think this driver needs to sort out if it supports > > this > > feature or not, and advertise as such rather than leaving userspace > > in the dark. > > By the way, what are the typical use-cases for AP scanning? > > I know that hostapd does a passive scan on the AP interface on the > assumption that the driver/firmware will gather channel survey data, > but > that's not a universally applicable assumption. Not all > implementations > will do that. We have someone wanting it for onboarding/configuring a new headless device. Where on boot, if it is unconfigured, it starts an AP and waits for a client to configure it. A client would connect, have the device scan and present available networks. The client then selects a network and provides credentials. The new device can then switch back to station mode and connect. This is a relatively common practice I've seen with IoT devices. Other than this I cant see much else of a use case besides, like you mentioned, gathering survey data to choose a low load channel (ACS its called I think?) Sadly this onboarding use case is quite perfect for DPP, but since Apple came up with their own protocol DPP won't work for any products that want cross compatibility... > > Kind regards, > Alvin > > > > > diff --git > > a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c > > b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c > > index fb727778312c..b6a50e65dbf6 100644 > > --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c > > +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c > > @@ -7729,6 +7729,8 @@ struct brcmf_cfg80211_info > > *brcmf_cfg80211_attach(struct brcmf_pub *drvr, > > #endif > > } > > > > + wiphy->features |= NL80211_FEATURE_AP_SCAN; > > + > > return cfg; > > > > detach:
