Disabling SMPS (Spatial multiplexing power save) when 802.11n is not used

Jose Blanquicet blanquicet at gmail.com
Mon Mar 21 01:45:37 PDT 2016


On Fri, Mar 18, 2016 at 6:54 PM, Jouni Malinen <j at w1.fi> wrote:
> On Fri, Mar 18, 2016 at 05:13:28PM +0100, Jose Blanquicet wrote:
>> I am using the Marvell driver sd8887 without any particular wpa_supplicant
>> configuration.
>> I also agree that your fix is more appropriated. I tried it and it
>> works also with
>> Marvell driver.
> Thanks.
>> I think that mac80211_hwsim does not take into account
>> smps_mode parameter when ht is disabled, which is right. But instead,
>> Marvell driver and maybe others report error -22 (Invalid argument) if they
>> receive smps_mode and it is set to a value different than OFF; of course
>> when disable_ht=1.
> Well, wpa_supplicant should not really be adding this attribute in such
> a case and I'll push in the fix for that.

I agree. Thanks!

>> On the other hand, I would like to make a question (I do not know if it should
>> be done in another discussion, if so let me know and I will create a new one).
>> The fact is that I have been able to use a, g, n and ac 802.11 modes but not
>> b. I get 802.11n or ac using disable_ht and disable_vht parameters.
>> Additionally, if I disable both parameters I get 802.11g mode and if I also set
>> frequency to a channel in 5GHz I get 802.11a mode. But I do not know how
>> to properly set the network parameters to enable 802.11b mode. How can I
>> do this?
> I don't think wpa_supplicant supports this. You can use hostapd to be
> configure AP with hw_mode=b if you need to configure this special (i.e.,
> obsolete..) case.

I know nobody will use 802.11b mode but in order to get the Wi-Fi
Alliance Certification in 802.11n, the system must be able to be
configured in a/b/g/n modes. Therefore, as I explained before, I was
trying to understand how to set properly the network parameters to get
all those modes. The wpa_supplicant already provides the way to enable
a/g/n/ac modes, thus I would expect that it also provides a way to use
b mode.

As you told, the hostapd provides very easy way to configure the mode
but I will always try to keep the system as simple as possible,
therefore I would add an additional module, hostapd in this case, only
if it is absolutely required.

Best regards,

Jose Blanquicet

> --
> Jouni Malinen                                            PGP id EFC895FA

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