le coded phy scanning on nRF52811

Hello,
I'm trying to use nRF52811 with apps/blehci as bluetooth controller which is connected via uart hci.
Scan on 1Mbps PHY is OK, but scan on coded phy has problem.
Here is detailed explanation.
- Environment:
- mcu nrf52811
- tool chain gcc version 9.3.1 20200408 (release) (GNU Arm Embedded Toolchain 9-2020-q2-update)
- mynewt-core 1.8.0
- mynewt-nimble 1.3.0
- mcu is connected to linux host (Linux 29b841b 4.19.118 armv6l) via uart.

- syscfg setting
`MCU_TARGET: nRF52811`
`MCU_LFCLK_SOURCE: LFRC`
`BLE_LL_CFG_FEAT_LE_CODED_PHY: 1`
`BLE_EXT_ADV: 1`
- syscfg.vals.BLE_CONTROLLER:
`TIMER_0: 0`
`TIMER_5: 1`
`OS_CPUTIME_FREQ: 32768`
`OS_CPUTIME_TIMER_NUM: 5`

- What I tried:
Following commands was tested with uart tx/rx is monitored by oscilloscope
- `btattach -B /dev/ttyAMA0 -P h4 -S 1000000`
- `bluetoothctl`
- `scan on`
- scan start with 1M phy and coded phy (1)
- `scan off`
- `hcitool cmd 08 31 03 04 04`
- set default phy coded only
- `bluetoothctl`
- `scan on`
- scan start with coded phy (2)
- `scan off`
- Expected result:
- scan result of (1) contains both of 1M phy devices and coded phy devices
- scan result of (2) contains coded phy devices
- both of (1) and (2) is extended scan
- Actual result:
- scan result of (1) contains only 1M phy devices
- scan result of (2) contains no devices
- both of (1) and (2) is extended scan

I think uart hci communication host and controller, extended scan ,and 1Mbps phy are ok.
I'm wondering if there is bug on coded phy, or I have incorrect configuration.
Thanks.

Start with apps/blehci and reproduce the reported scan sequences using the nRF52811 syscfg values and monitored UART HCI traffic. Compare the 1M-and-coded-PHY scan with the coded-only scan, including the `hcitool cmd 08 31 03 04 04` setting. Done means coded-PHY devices appear in both expected scan modes.

Written by the indexing model from the issue text.