Re: [PATCH v2 4/6] wireless: Add util method to get channel index from frequency.

[Ben Greear <greearb@candelatech.com>]

On 04/17/2012 06:40 PM, Johannes Berg wrote:
> On Tue, 2012-04-17 at 10:46 -0700, greearb@candelatech.com wrote:
>> From: Ben Greear<greearb@candelatech.com>
>>
>> Signed-off-by: Ben Greear<greearb@candelatech.com>
>> ---
>> :100644 100644 27f9561... be6fb62... M	include/net/cfg80211.h
>> :100644 100644 6cba001... 2fd0e97... M	net/wireless/util.c
>>   include/net/cfg80211.h |    7 +++++++
>>   net/wireless/util.c    |   24 ++++++++++++++++++++++++
>>   2 files changed, 31 insertions(+), 0 deletions(-)
>>
>> diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
>> index 27f9561..be6fb62 100644
>> --- a/include/net/cfg80211.h
>> +++ b/include/net/cfg80211.h
>> @@ -2388,6 +2388,13 @@ ieee80211_get_channel(struct wiphy *wiphy, int freq)
>>   }
>>
>>   /**
>> + * ieee80211_get_channel_idx - get channel index from wiphy for specified freq
>> + * @wiphy: the struct wiphy to get the channel for
>> + * @freq: the center frequency of the channel
>> + */
>> +extern int ieee80211_get_channel_idx(struct wiphy *wiphy, int freq);
>
> I prefer you drop the extern, but ...
>
>
>> +int ieee80211_get_channel_idx(struct wiphy *wiphy, int freq)
>> +{
>> +       enum ieee80211_band band;
>> +       struct ieee80211_supported_band *sband;
>> +       int i;
>> +       int rv = 0;
>> +
>> +       for (band = 0; band<  IEEE80211_NUM_BANDS; band++) {
>> +               sband = wiphy->bands[band];
>> +
>> +               if (!sband)
>> +                       continue;
>> +
>> +               for (i = 0; i<  sband->n_channels; i++) {
>> +                       if (sband->channels[i].center_freq == freq)
>> +                               return rv;
>> +                       rv++;
>> +               }
>> +       }
>> +
>> +       return NULL;
>> +}
>
>
> "return NULL"? Really?

Gah, that is wrong.

> Also, what use is the index? It's some kind of global channel index, but
> that's almost completely useless. I think you need a very very very good
> reason to have this function and you're not even stating a single one.

Well, it's used in the next patch that gets the survey info by index.

Wouldn't hurt my feelings to re-write how the get-survey() method
is called, but that would touch a lot of drivers, break out-of-tree drivers,
etc.

When you get a chance, please take a look at how the survey code
appears to work and let me know if you want it changed to take
channel objects instead of channel indexes.

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com