Nordic zephyr-sdk scan behaves differently than upstream zephyr

Question

I'm using an nfr52840 board. 
 I noticed that when using The 'zephry-sdk' v3.5.99-ncs1-1, when doing a passive scan using: 
 BT_LE_SCAN_ PASSIVE 
 which sets: 
 BT_LE_SCAN_PARAM(BT_LE_SCAN_TYPE_ PASSIVE , BT_LE_SCAN_OPT_FILTER_DUPLICATE, BT_GAP_SCAN_FAST_INTERVAL, BT_GAP_SCAN_FAST_WINDOW) 
 I get continuous duplicate advertisement packets 
 However using the upstream zephyr with exactly the same configuration, I only get each advertisement once (until the scan is stopped/restarted) 
 Note that I am not using any NRF connect specific code...This is pure zephyr. 
 Is there any way to get the upstream behavior when using the nordic zephyr-sdk branch?

Sigurd · Accepted Answer

Hi! 
 You are likely seeing this limitation here in the SoftDevice Controller: 
 DRGN-8628: Setting Filter_Duplicates in LE Set Scan Enable and LE Set Extended Scan Enable commands does not take effect 
 The host receives all advertisements from advertisers in advertising report events even if Filter_Duplicates is set in LE Set Scan Enable and LE Set Extended Scan Enable. Filter_Duplicates cannot guarantee that all duplicate advertising reports are filtered out, because the controller has a limited “cache” of known advertising reports. 
 Workaround: Filter out the duplicate advertising reports in the application. 
 
 https://docs.nordicsemi.com/bundle/ncs-latest/page/nrfxlib/softdevice_controller/limitations.html 
 Is there any way to get the upstream behavior when using the nordic zephyr-sdk branch? 
 I would generally recommend using the SoftDevice Controller, it's this Controller we qualify, it's is developed, tested, and supported by Nordic Semiconductor. But to use the Zephyr Bluetooth LE Controller instead, set CONFIG_BT_LL_SW_SPLIT to y in the prj.conf 
 https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/protocols/bt/ble/index.html#usage_in_samples

Nordic zephyr-sdk scan behaves differently than upstream zephyr

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