Re: [PATCH v4 1/6] nl80211/cfg80211: add radar detection command/event

[Victor Goldenshtein <victorg@ti.com>]

On 16/10/2012 21:01, Johannes Berg wrote:
> On Sun, 2012-10-14 at 16:48 +0200, Victor Goldenshtein wrote:
>
>> + * @radar_detect_timeout: this timeout indicates the end of the channel
>> + *	availability check for radar channels (in jiffies), only after this
>> + *	period the user may initiate the tx on the channel.
>> + * @cac_type: indicates that channel availability check is started for this
>> + *	channel type.
>
> You're missing docs for cac_started
>

missed that..

> I'll fix it if I don't have any comments on the other patches and the
> answer to my question below doesn't mean a change:
>
>> +++ b/net/wireless/nl80211.c
>> @@ -1411,6 +1411,7 @@ static int __nl80211_set_channel(struct cfg80211_registered_device *rdev,
>>   			result = -EINVAL;
>>   			break;
>>   		}
>> +		channel->cac_started = false;
>
> Why this? If the device supports channel contexts then maybe one vif
> could set the channel and the other could be doing radar detection? But
> anyway this only presets the channel, so nothing will happen until the
> AP interface is started? So basically I don't understand this at all.

Here we just clearing the cac_started flag, this was previously done in 
the ieee80211_do_stop() for the "sdata->wdev.preset_chan", but as we 
didn't want to modify cfg80211 fields from mac I suggested to move it here.

I"ll try to clarify things a bit, the channel availability check (CAC) 
could be started during:
1. AP init phase - when AP is configured on DFS channel.
2. As a result of a channel switch - AP moved to a DFS channel.

In both cases we set the cac_started flag from the 
nl80211_start_radar_detection() and clear it:
1. As a result of radar event.
2. In __nl80211_set_channel() - to cover the case when the CAC was 
initiated on a "preset_chan" (during AP init phase) and the IF was 
removed before the AP was even started (local->oper_channel wasn't set yet).


-- 
Thanks,
Victor.