drivers: spi: spi_loopback: drivers.spi.nrf_fast fails

[katgiadla]

Describe the bug Test tests/drivers/spi/spi_loopback/drivers.spi.nrf_fast fails.

Observed for nrf54h20dk@0.9.0/nrf54h20/cpuapp.

To Reproduce Steps to reproduce the behavior:

1. have nrf54h20dk/nrf54h20/cpuapp connected
2. go to your zephyr dir
3. call ./scripts/twister -s drivers.spi.nrf_fast -p nrf54h20dk@0.9.0/nrf54h20/cpuapp --device-testing --device-serial /dev/ttyACM0 -v --inline-logs --west-flash="--erase" --fixture spi_loopback
4. See console output with error

Expected behavior Valid console output

Impact Not clear

Logs and console output

*** Booting Zephyr OS build v4.0.0-837-gb88d0bf8c7ee ***
Running TESTSUITE spi_loopback
===================================================================
START - test_spi_loopback
I: SPI test on buffers TX/RX 0x2f0156a0/0x2f015680, frame size = 8
I: SPI test slow config
I: Start complete multiple
E: Buffer contents are different: 0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0x61,0x62,0x63,0x64,0x65,0x66,0x2d,0x00,
E:                            vs: 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

    Assertion failed at zephyr/tests/drivers/spi/spi_loopback/src/spi.c:145: spi_complete_multiple: (1 is true)
Buffer contents are different
 FAIL - test_spi_loopback in 0.048 seconds
===================================================================
TESTSUITE spi_loopback failed.

------ TESTSUITE SUMMARY START ------

SUITE FAIL -   0.00% [spi_loopback]: pass = 0, fail = 1, skip = 0, total = 1 duration = 0.048 seconds
 - FAIL - [spi_loopback.test_spi_loopback] duration = 0.048 seconds

------ TESTSUITE SUMMARY END ------

===================================================================
PROJECT EXECUTION FAILED

Environment (please complete the following information):

• OS: Ubuntu 20.04.1 LTS
  • Toolchain Zephyr SDK 0.16.8
  • Commit SHA or Version used: v4.0.0-837-gb88d0b

Additional information:

• used set of pins:

  spi130_default: spi130_default {
      group1 {
          psels = <NRF_PSEL(SPIM_SCK, 0, 0)>,
              <NRF_PSEL(SPIM_MISO, 0, 6)>,
              <NRF_PSEL(SPIM_MOSI, 0, 7)>;
      };
  };

[tbursztyka]

Just to make sure, I am not aware that SPI_MODE_LOOP is supported by nrf's controllers, so you did short both miso/mosi lines physically?