On 24 September 2014 16:35, Ben Greear <greearb@xxxxxxxxxxxxxxx> wrote:
> On 09/24/2014 12:51 AM, Michal Kazior wrote:
>> On 24 September 2014 02:26, <greearb@xxxxxxxxxxxxxxx> wrote:
>> [...]
>>>
>>> +static struct ieee80211_sta_vht_cap ath10k_create_vht_cap(struct ath10k
>>> *ar,
>>> + bool
>>> use_cfg_chains)
>>> {
>>> struct ieee80211_sta_vht_cap vht_cap = {0};
>>> u16 mcs_map;
>>> int i;
>>> + int nrf = ar->num_rf_chains;
>>> +
>>> + if (use_cfg_chains && ar->cfg_tx_chainmask)
>>> + nrf = get_nss_from_chainmask(ar->cfg_tx_chainmask);
>>
>>
>> Is use_cfg_chains really necessary here? Is setting tx/rx chainmask to
>> 0x0 make any sense at all? Shouldn't we deny it or make it fallback to
>> the supported tx/rx chainmask values?
>
> It would cause the logic to flip back to the defaults, so seems mildly
> useful. I'm not sure
> upper layers would ever let it be < 1 though.
0 is a valid argument as far as upper layers are concerned and should
be treated as "use all available antennas" (see `iw list` output
before ever setting antenna, after setting to, e.g. 1 and then to 0).
This implies current set_antenna() implementation is actually buggy
(pdev param should involve using supp_tx/rx_chainmask). Your
assumption in recent patches is also incorrect as antenna mask = 0
should imply max nss, not 1.
Michał
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