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

Jose Blanquicet blanquicet at gmail.com
Fri Mar 18 01:20:17 PDT 2016


SMPS (Spatial multiplexing power save) is a feature proposed in 802.11n 
to reduce power consumption. When device is playing in Access Point and 
802.11n mode is disable setting disable_ht = 1, the HT Capabilities 
(conf->ht_capab) are "cleaned" (Set to zero) in function 
wpa_supplicant_conf_ap_ht, but the value 0 does not actually clean the
capabilities, instead it is being set to use SMPS_STATIC:

	#define HT_CAP_INFO_SMPS_STATIC			((u16) 0)
	#define HT_CAP_INFO_SMPS_DYNAMIC		((u16) BIT(2))
	#define HT_CAP_INFO_SMPS_DISABLED		((u16) (BIT(2) | BIT(3)))

Therefore, when the beacons parameters are configured, it results in an 
error because SMPS is set to SMPS_STATIC mode in a non-802.11n configuration:

	nl80211: Beacon set failed: -22 (Invalid argument)

Best regards,

Jose Blanquicet

 wpa_supplicant/ap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


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