nrf5340 DK is unable to utilize DLE max package size

[Dumam]

Hi,

From some time I'm trying to fix problems with throughput sample.
I don't know why, but after setting data len parameter to any value it's constantly sets 27.

uart:~$ config data_length 100
LE Data Packet Length set to: 100
[00:00:34.655,975] <inf> main: LE Data length update pending, since 1135607
[00:00:36.110,992] <inf> main: [local] LE data len updated: TX (len: 27 time: 2120) RX (len: 27 time: 2120), done: 1183285
[00:00:36.111,022] <inf> main: LE Data Length updated
uart:~$ config data_length 100
LE Data Packet Length set to: 100
[00:00:39.185,546] <inf> main: LE Data length update pending, since 1284032

Same code for Particle Xenon with nrft52840 works fine so I guess it's config problem somewhere between network and application core.

https://github.com/DuMaM/bitly_nrf5x/blob/main/prj_nrf5340dk_nrf5340_cpuapp.conf

https://github.com/DuMaM/bitly_nrf5x/blob/main/child_image/hci_rpmsg.conf

Please help me in setting this up.

[Dumam]

Ok, I solved my issues by pure luck.
After searching around something which has value 27 it turned out that my child img config is not loading.
I investigated it a bit more and it turned out,  since 2.0.0 pattern for the child project config is a bit different.

instead of hci_rpmsg.conf it should be hci_rpmsg_nrf5340dk_nrf5340_cpuapp.conf

It's due to this code in muliimage.cmake

      if(NOT "${CONF_FILE_BUILD_TYPE}" STREQUAL "")

        set(child_image_conf_fragment ${ACI_CONF_DIR}/${ACI_NAME}_${CONF_FILE_BUILD_TYPE}.conf)

      else()

        set(child_image_conf_fragment ${ACI_CONF_DIR}/${ACI_NAME}.conf)

      endif()

      if (EXISTS ${child_image_conf_fragment})

        add_overlay_config(${ACI_NAME} ${child_image_conf_fragment})

      endif()

And this one in zephyr\cmake\modules\configuration_files.cmake

if(DEFINED CONF_FILE)

  # This ensures that CACHE{CONF_FILE} will be set correctly to current scope

  # variable CONF_FILE. An already current scope variable will stay the same.

  set(CONF_FILE ${CONF_FILE})

  # CONF_FILE has either been specified on the cmake CLI or is already

  # in the CMakeCache.txt. This has precedence over the environment

  # variable CONF_FILE and the default prj.conf

  # In order to support a `prj_<name>.conf pattern for auto inclusion of board

  # overlays, then we must first ensure only a single conf file is provided.

  string(REPLACE " " ";" CONF_FILE_AS_LIST "${CONF_FILE}")

  list(LENGTH CONF_FILE_AS_LIST CONF_FILE_LENGTH)

  if(${CONF_FILE_LENGTH} EQUAL 1)

    # Need the file name to look for match.

    # Need path in order to check if it is absolute.

    get_filename_component(CONF_FILE_NAME ${CONF_FILE} NAME)

    if(${CONF_FILE_NAME} MATCHES "prj_(.*).conf")

      set(CONF_FILE_BUILD_TYPE ${CMAKE_MATCH_1})

      set(CONF_FILE_INCLUDE_FRAGMENTS true)

    endif()

  endif()

elseif(CACHED_CONF_FILE)

Second part of code is defining CONF_FILE_BUILD_TYPE so it makes unable for muliimage.cmake to pick up correct default conf file.