On 1/15/2021 3:57 PM, Alvin Šipraga wrote:
Hi Arend, On 1/15/21 3:10 PM, Arend Van Spriel wrote:+ Johannes - netdevs On 1/14/2021 5:36 PM, 'Alvin Šipraga' via BRCM80211-DEV-LIST,PDL wrote:Add support for CQM RSSI measurement reporting and advertise the NL80211_EXT_FEATURE_CQM_RSSI_LIST feature. This enables a userspace supplicant such as iwd to be notified of changes in the RSSI for roaming and signal monitoring purposes.The more I am looking into this API the less I understand it or at least it raises a couple of questions. Looking into nl80211_set_cqm_rssi() [1] two behaviors are supported: 1) driver is provisioned with a threshold and hysteresis, or 2) driver is provisioned with high and low threshold. > The second behavior is used when the driver advertises NL80211_EXT_FEATURE_CQM_RSSI_LIST *and* user-space provides more than one RSSI threshold. In both cases the same driver callback is being used so I wonder what is expected from the driver. Seems to me the driver would need to be able to distinguish between the two behavioral scenarios. As there is no obvious way I assume the driver should behave the same for both cases, but again it is unclear to me what that expected/required behavior is.It will only provision the driver according to behaviour (1) if 0 or 1 thresholds are being set AND the driver implements set_cqm_rssi_config(). But it says in the documentation for the set_cqm_rssi_range_config() callback[1] that it supersedes set_cqm_rssi_config() (or at least that there is no point in implementing _config if range_config is implemented). In that case, and if just one threshold is supplied (with a hysteresis), then a suitable range is computed by cfg80211_cqm_rssi_update() and provided to set_cqm_rssi_range_config(). I guess the implication here is that the two behaviours are functionally equivalent. I'm not sure I can argue for or against that because I don't really know what the semantics of the original API were supposed to be, but it seems reasonable. As a starting point - and since the firmware behaviour is very close already - I implemented only set_cqm_rssi_range(). I have been testing with iwd, which by default sets just a single threshold and hysteresis, and the driver was sending notifications as would be expected.
OK. I overlooked that there were two different callbacks involved. So I will review the patch with that knowledge. What wifi chip did you test this with and more importantly which firmware version?
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