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enable/disable the pre-CAC

cfg80211tool wifiX preCACEn 0/1

The following command is used to set intermediate channel:

cfg80211tool wifix interCACChan <non_dfs_chan_num>

The following command is used to display pre-CAC lists:

radartool -I wifiX showprecaclists

Only one VHT80 segment (segment 42) as non DFS segment operates. Therefore, intermediate channels must be mapped to this segment. To achieve this, the following code path enhancements are implemented:

  • “ieee80211_ucfg_set_freq_internal(): Identify if channel to be configured is DFS channel. If so instead of using configured channel, configure intermediate channel as operating channel. Configure VHT80 mode while using intermediate channel
  • “dfs_decide_precac_preferred_chan(): Save current mode and priorities primary and secondary segment of configured channel for pre-CAC.
  • “ieee80211_autochan_switch_chan_change_csa(): After pre-CAC done, check if desired channel is in precac done list. If so, change channel from intermediate channel to configured DFS channel. Also change mode to VHT160. This functionality is supported only in ETSI domain where off-channel CAC is allowed. Also, it is supported on offload chipsets with Agile DFS capability, such as IPQ807xA, in addition to QCA9984 chipsets in legacy platforms. If radar is detected on configured DFS channel while performing off-channel CAC, AP remains in intermediate channel with VHT80 or HE80 mode. Any channel change due to iwconfig is only handled.