RTL8720DN in promisc mode: how to get PLCP headers?

Technical Discussion
1

Hi all,

I am using the RTL8720DN in promiscuous mode, I configure it with

wifi_set_promisc(RTW_PROMISC_ENABLE_2, promisc_callback, 1);

This works well.

Now I want to gain access to the PLCP headers of the received frames, notably because I need to know the MCS index that was used for transmission. From wifi_constants.h I understand that in order to be given the rtw_rx_info_t structure (defined in wifi_structures.h) of the received frames I have to use RTW_PROMISC_ENABLE_4 instead of RTW_PROMISC_ENABLE_2.

Unfortunately when I init my board with

wifi_set_promisc(RTW_PROMISC_ENABLE_4, promisc_callback, 1);

my callback never gets called, although I have made sure that the CONFIG_UNSUPPORT_PLCPHDR_RPT flag is defined and set.

Am I missing something, or is it a malfunction of the Realtek firmware?

Thanks for help !