Re: [PATCH 2/2] Revert "wl1271: Change supported channel order for a more optimal scan"

[Gery Kahn <geryk@ti.com>]

On 11/10/2010 1:42 PM, Juuso Oikarinen wrote:
> On Wed, 2010-11-10 at 12:36 +0100, ext Gery Kahn wrote:
>> On 11/10/2010 01:21 PM, Juuso Oikarinen wrote:
>>> On Wed, 2010-11-10 at 12:18 +0100, ext Gery Kahn wrote:
>>>> On 11/10/2010 12:27 PM, juuso.oikarinen@nokia.com wrote:
>>>>> From: Juuso Oikarinen<juuso.oikarinen@nokia.com>
>>>>>
>>>>> This reverts commit fa21c7a9e4be439e217fe72edbd39b643b643791.
>>>>>
>>>>> The reverted patch caused more harm than benefit.
>>>>>
>>>>> Signed-off-by: Juuso Oikarinen<juuso.oikarinen@nokia.com>
>>>>>
>>>> Just couple words what harm it was?
>>> The harm is that the supported channels are reported to user-space in
>>> the order they are registered in the driver. The result of that is quite
>>> messy in userspace PoV.
>>>
>>> -Juuso
>>>
>> Thank you for answer.
>>
>> The reason of doing such channel sorting was channel overlapping.
>>
>> Let's say for 11a (bandwidth 20MHz) it is not a problem.
>> While 11g, preferred channel sorting would be 1,6,11,...
>>
>> Gery
> Yes, this is why we had this reordering in the first place.
>
> One benefit of sorting channels would be to get faster results for the
> whole band, as there are responses from the overlapping channels too.
>
Another benefit is to have max band coverage with minimum prob reqs.
The overlapping answers have collisions, which discard all packets and 
if timeout scan -
no responce from AP or even silence in channel.
> Currently the the scanning code however waits for all channels to be
> scanned before sending results to userspace, so this benefit is not
> utilized, and removing this patch makes no difference in that sense.
>
> To take advantage of channel reordering, some other changes are needed
> too. And the reordering needs to be performed in the mac80211/cfg80211
> level (I actually earlier submitted a RFC patch doing just this.)
>
> -Juuso
>
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>