Re: [PATCH v3] wifi: cfg80211: check radio iface combination for multi radio per wiphy

[Johannes Berg <johannes@sipsolutions.net>]

On Wed, 2024-09-11 at 18:21 +0530, Karthikeyan Periyasamy wrote:
> 
> On 9/11/2024 3:12 PM, Johannes Berg wrote:
> > On Wed, 2024-09-04 at 16:59 +0530, Karthikeyan Periyasamy wrote:
> > > Currently, wiphy_verify_combinations() fails for the multi-radio per wiphy
> > > due to the condition check on global interface combination that DFS only
> > > works on one channel.
> > 
> > As it should, really.
> > 
> > > In a multi-radio scenario, global interface
> > > combination encompasses the capabilities of all radio combinations, so it
> > > supports more than one channel with DFS.
> > 
> > No, that's not correct, it doesn't.
> 
> But the attribute comment section clearly says the Global iface 
> combination encompass all radio combination as below
> 
> * @NL80211_ATTR_WIPHY_INTERFACE_COMBINATIONS: Nested attribute listing * 
> the
> *      supported interface combinations for all radios combined. In each
> *      nested item, it contains attributes defined in
> *      &enum nl80211_if_combination_attrs.
> 
> Is my understanding incorrect ?

I guess it depends on how you interpret "combined". It must be something
that can actually be done *regardless* of radio assignment, to be
compatible with older userspace.

So if you think "combined" == "superset of all radios" then your
understanding is incorrect. You need to think "combined" == "what the
device can do without caring about radio assignment".

johannes