47d668219b
Currently the driver uses a global safe channel list, and also keeps another safe channel list in policy mgr which results in duplicate copies of the same thing. Also there are many possible issues which are seen if the global list implementation is used. Issue 1:- The global unsafe ch list is maintained for each channel and is updated as part of ACS scan cb. So if a user does ACS again and again ( SAP on off) then the result of unsafe channels of the previous ACS request would be updated as part of the ACS cb of the new ACS scan request. In the function of sap_get_freq_list, the driver filters out the channels which are unsafe, and the same channels are not chosen as the best channel for SAP operation. Now the filtration of the channels would happen according to the previous ACS request, and the driver would remove the channels from the ACS scan list. But those channels were unsafe when the previous ACS happened, and may not be unsafe now, and can be used to turn on the SAP (can be chosen as the best channel) Issue 2:- If the channels are truly unsafe, then the driver filters out the channel in the function sap_get_freq_list, and do not chose them for the SAP. It may happen that the channel list that the driver preferred as part of do acs becomes unsafe, and the channels that were unsafe at the time of do acs becomes safe while the driver was scanning the ACS channels to find other APs. Now since the channels that were unsafe at the time of ACS req are safe now, they could have been chosen as the best channel but they were not scanned, so the ACS channel weight of these channels would remain maximum, and they would be sorted at last of the sorted list. Also the channels that were as part of the ACS channels list became unsafe, hence the driver would also assign maximum weight to them, and they would too become unusable channels. This would result in all channels having the same weight that is maximum weight, and so the sorting algorithm does not have to sort any channel now since all of the weights are same. The first channel in the sorted list would be channel number 1 of 2.4Ghz, and would get chosen, but this may not be correct if the HW mode is 5ghz only. Fix:- Safe and unsafe channels can be checked by using policy mgr safe channel list too, so it is better to keep just one unsafe channel list. The driver would not filter out the unsafe channels for ACS scan, and would filter out the unsafe channels as part of the ACS scan done callback. Change-Id: Ief236db9e73864e5cb2d290a8106799f9e80f82d CRs-Fixed: 2530241
This is CNSS WLAN Host Driver for products starting from iHelium