Re: [RFC V3 03/11] nl80211: add support for gscan

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

On 13-12-2016 23:29, Johannes Berg wrote:
> On Tue, 2016-12-13 at 21:09 +0100, Arend Van Spriel wrote:
>>  
>>> There's a bit of a weird hard-coded restriction to 16 channels too,
>>> that's due to the bucket map?
>>
>> Uhm. Is there? I will check, but if you can give me a pointer where
>> to look it is appreciated.
> 
> Just look for "< 16" or "<= 16" or so in the patch. I do think that's
> because the channel map is a u16 though, not sure we'd want to change
> that.

Had to look for "> 16" ;-)

> +	/* ignore channels if band is specified */
> +	if (band_select)
> +		return 0;
> +
> +        nla_for_each_nested(chan,
tb[NL80211_GSCAN_BUCKET_ATTR_CHANNELS], rem) {
> +                num_chans++;
> +        }

Here an instance of the tab vs. space issue you mentioned. Will go over
the patch and fix that.

> +	if (num_chans > 16)
> +		return -EINVAL;

I suspect this is the restriction you were referring to. There is no
reason for this although the android wifi hal has max 16 channels in a
bucket so I might have picked that up. So could a driver have a similar
limit and should we add such to the gscan capabilities? For instance our
firmware api has a nasty restriction of 64 channels for all buckets
together, eg. can do 4 buckets of 16 channels each.

Regards,
Arend