Re: [PATCH 06/13] wifi: nl80211: send iface combination to user space in multi-hardware wiphy

[Vasanthakumar Thiagarajan <quic_vthiagar@quicinc.com>]

On 3/28/2024 7:03 PM, Johannes Berg wrote:
> On Thu, 2024-03-28 at 12:59 +0530, Karthikeyan Periyasamy wrote:
>>
>> + *	When describing per-hardware combinations in multi-hardware in
>> + *	one wiphy model, the first possibility can further include the finer
>> + *	capabilities like below
> 
> Not sure I'd say "below" rather than e.g. "like this:"
> 
>> + *	hw_chan_idx = 0, numbers = [ #{STA} <= 1, #{AP} <= 1 ],
>> + *	channels = 1, max = 2
>> + *	=> allows a STA plus an AP interface on the underlying hardware mac
>> + *	   advertised at index 0 in wiphy @hw_chans array.
>> + *	hw_chan_idx = 1, numbers = [ #{STA} <= 1, #{AP} <= 2 ],
>> + *	channels = 1, max = 3
>> + *	=> allows a STA plus two AP interfaces on the underlying hardware mac
>> + *	   advertised at index 1 in wiphy @hw_chans array.
> 
> Have you checked the rst output for this? Seems likely that's not going
> to be great with that formatting, but I haven't checked.
> 
>> + * @NL80211_IFACE_COMB_PER_HW_COMB_HW_IDX: u8 attribute specifying the index
>> + *	to the wiphy @hw_chans list for which the iface combination is being
>> + *	described.
> 
> "@hw_chans" doesn't make sense here, this is nl80211, it should refer to
> some attribute
> 
> but why didn't you just _say_ in the patch 2 discussion that it's used
> here ...
> 
>> + * @NL80211_IFACE_COMB_PER_HW_COMB_LIMITS: nested attribute containing the
>> + *	limits for the given interface types, see
>> + *	&enum nl80211_iface_limit_attrs.
>> + * @NL80211_IFACE_COMB_PER_HW_COMB_MAXIMUM: u32 attribute giving the maximum
>> + *	number of interfaces that can be created in this group. This number
>> + *	does not apply to the interfaces purely managed in software.
>> + * @NL80211_IFACE_COMB_PER_HW_COMB_NUM_CHANNELS: u32 attribute specifying the
>> + *	number of different channels that can be used in this group.
>> + * @NUM_NL80211_IFACE_COMB_PER_HW_COMB: number of attributes
>> + * @MAX_NL80211_IFACE_COMB_PER_HW_COMB: highest attribute number
>> + */
>> +enum nl80211_if_comb_per_hw_comb_attrs {
>> +	NL80211_IFACE_COMB_PER_HW_COMB_UNSPEC,
>> +	NL80211_IFACE_COMB_PER_HW_COMB_HW_IDX,
>> +	NL80211_IFACE_COMB_PER_HW_COMB_LIMITS,
>> +	NL80211_IFACE_COMB_PER_HW_COMB_MAXIMUM,
>> +	NL80211_IFACE_COMB_PER_HW_COMB_NUM_CHANNELS,
> 
> Almost all these attributes duplicate - including their docs -
> attributes from enum nl80211_if_combination_attrs. Is it really worth
> doing that, rather than adding NL80211_IFACE_COMB_HW_IDX and documenting
> the different uses of the attribute set?
> 

I agree, more duplication. So we have to have the per_hw_comb_attrs
defines like below?

enum nl80211_if_comb_per_hw_comb_attrs {
	NL80211_IFACE_COMB_PER_HW_COMB_UNSPEC,
	NL80211_IFACE_COMB_PER_HW_COMB_HW_IDX = 			
			NL80211_IFACE_COMB_NUM_CHANNELS + 1,
	/* keep last */
	NUM_NL80211_IFACE_COMB_PER_HW_COMB,
	MAX_NL80211_IFACE_COMB_PER_HW_COMB =
			NUM_NL80211_IFACE_COMB_PER_HW_COMB - 1
};

Vasanth