Re: [PATCH] ath9k: Added get_survey callback in order to get channel noise

[Benoit PAPILLAULT <benoit.papillault@free.fr>]

Jouni Malinen a écrit :
> On Tue, 2010-04-27 at 15:08 -0700, Benoit Papillault wrote:
>   
>> +static int ath9k_get_survey(struct ieee80211_hw *hw, int idx,
>> +			     struct survey_info *survey)
>>     
>
>   
>> +	struct ieee80211_conf *conf = &hw->conf;
>> +
>> +	 if (idx != 0)
>> +		return -ENOENT;
>> +
>> +	survey->channel = conf->channel;
>>     
>
> Are there any plans on providing this information from all channels? I
> have assumed that the survey command was supposed to be used for
> surveying all channels (e.g., to get information for auto-channel
> selection) and returning something for the current channel is quite
> limited subset of that. In other words, I would like to be able to run a
> scan of all channels and then use NL80211_CMD_GET_SURVEY to fetch
> additional per-channel information like noise (and also channel usage
> statistics in case of ath9k) from the scanned channels.
>
> - Jouni
>   
Hi Jouni,

I dig into the source code to understand the use of "idx" and having the 
value for all scanned channels sounds a good plan. However :

- when doing a normal scan (iw dev wlan0 scan), the noise floor 
calibration is started in a special mode, so I don't know if the results 
is accurate enought.

- the first calibration takes some times .... more than the scan itself. 
So, you cannot get a valid value before switching to the next channel.

Anyway, how idx is supposed to be used? From 0 ... up to the callback 
returning -ENOENT ?
Do we need to keep a table with noise for each channel and return those 
where we have a value, in which case idx cannot be used as an index into 
this table ?

Regards,
Benoit