On 2018-12-18 18:39, Johannes Berg wrote:
On Fri, 2018-11-30 at 14:04 +0530, vamsi krishna wrote:
The drivers with capability to filter scan results with different rssi
thresholds for different bands shall indicate the support to user
space by
setting %NL80211_EXT_FEATURE_SCHED_SCAN_BAND_SPECIFIC_RSSI_THOLD in
wiphy->ext_features. The drivers that support this feature shall use
rssi
values from @band_specific_min_rssi_thold for scan results filtering
and
shall not use min_rssi_thold anymore.
Is there much point in this?
It seems to me that userspace will not really do anything different if
it knows what's supported - it's probably easier for it (or cfg80211?)
to just set the global min_rssi to the minimum over all bands, and
treat
this as we do most things in scheduled scan - an optimisation that
doesn't really need a feature advertisement?
I think that would simplify things somewhat.
I think the driver capability advertisement will provide more
flexibility to users in few cases, e.g., earlier, say if userspace is
programming -65dBm as min_rssi_thold common for all bands and with the
new implementation it may choose to configure -60dBm for 5GHz band and
-70dBm for 2.4GHz band for better user experience and power saving(with
filtering out unwanted 5GHz bssids). If the user configures -60dBm and
-70dBm thresholds for the old drivers without band specific threshold
support, it could result in unnecessary wakeups for 5GHz bssids with
rssi between -65dBm and -70dBm (compared to the old case of configuring
single threshold of -65dBm). So, I think it is better to keep the
capability advertisement.
+ * @NL80211_ATTR_SCHED_SCAN_MIN_RSSI: Nested attribute that carries
the band
+ * specific minimum rssi thresholds for the bands defined in enum
+ * nl80211_band. The minimum rssi threshold value(s32) specific to a
band
+ * shall be encapsulated in attribute with type value equals to one
of the
+ * NL80211_BAND_* defined in enum nl80211_band. For example, the
minimum
+ * rssi threshold value for 2.4GHz band shall be encapsulated within
an
+ * attribute of type NL80211_BAND_2GHz. And one or more of such
attributes
+ * will be nested within this attribute. If min rssi sub attribute is
not
+ * included for any band, then %NL80211_SCAN_RSSI_THOLD_OFF will be
used
+ * as minimum rssi threshold for scan result filtering.
+ * If a scan result received in a particular band has lesser rssi
than the
+ * rssi threshold specified for that band, then the scan result shall
be
+ * filtered out. The rssi thresholds specified in matchsets along
with ssid
+ * or bssid attribute will have higher precedence than the thresholds
+ * mentioned in this attribute while checking rssi.
It seems that this should be with the existing
NL80211_SCHED_SCAN_MATCH_ATTR_RSSI, not in this level namespace.
The band specific rssi thresholds that are being configured are global
across all matchsets whereas NL80211_SCHED_SCAN_MATCH_ATTR_* attributes
are mostly specific to each matchset. Hence I choose to define
attributes in higher level namespace. In future, whenever we want to
adding support for rssi thresholds per band and per matchset, we can
define attributes within NL80211_SCHED_SCAN_MATCH_ATTR_* namespace
level.
Thanks & Regards,
Vamsi
