SPI Peripheral Power Consumption much higher than nrf5 SDK

Question

Hi,
We are currently migrating our nrf5 SDK code to NCS 2.2.0 on a custom nrf52833 board (using a .overlay file on the DK).

Our power consumption for the same peripheral is ~6.1 uA average, as opposed to our expected ~3.5 uA average on nrf5SDK - but we are able to achieve around ~4 uA average by not calling the SPI module at all.

Some points to note before the code:

According to the data sheet of the peripheral - we should be working in NRF_SPI_MODE_3 on nrf5 SDK, which seems to translate to | CPOL | CPHA on zephyr. However - if we try to use this mode, SPI does not work at all, and we see a very high baseline on PPK.
This peripheral and another peripheral on our board share 2 pins: SCK, and another pin which is MISO for this peripheral, and MISO_MOSI for the other peripheral. This does not cause problems on nrf5 SDK.

Our SPI usage is as follows:

const struct gpio_dt_spec spec = {
.dt_flags = GPIO_ACTIVE_LOW,
.pin = 5,
.port = DEVICE_DT_GET(DT_NODELABEL(gpio0))
}; 

struct spi_cs_control spi_cs = {
    .gpio = spec,
    /* delay in microseconds to wait before starting the transmission and before releasing the CS line */
    .delay = 10,
};

#define SPI_CS (&spi_cs)

struct spi_config spi_cfg = {
    .frequency = 0x4000000,
    .operation = SPI_OP_MODE_MASTER | SPI_TRANSFER_MSB | SPI_WORD_SET(8), // | SPI_MODE_CPOL | SPI_MODE_CPHA,
    .cs = SPI_CS,
};

const struct device *spi1_dev =  DEVICE_DT_GET(DT_NODELABEL(spi1));

void acc_spi_write(uint8_t cmd, uint8_t val)
{
    uint8_t com[2] = { cmd, val };
    struct spi_buf tx_buf[1] = {
        {
            .buf = com,
            .len = 2
        }
    };

    struct spi_buf_set tx_bufs = {
        .buffers = tx_buf,
        .count = 1
    };

    int ans = spi_transceive(spi1_dev,&spi_cfg,&tx_bufs,NULL);
    if(ans)
    {
        printk("SPI write failed - %d\n",ans);
    }
}

And in the overlay file:

&pinctrl {

    // acc
    status = "okay";
    spi1_default: spi1_default {
        group1 {
            psels = <NRF_PSEL(SPIM_SCK, 0, 4)>,
                <NRF_PSEL(SPIM_MOSI, 0, 11)>,
                <NRF_PSEL(SPIM_MISO, 1, 9)>;
        };
    };

    spi1_sleep: spi1_sleep {
        group1 {
            psels = <NRF_PSEL(SPIM_SCK, 0, 4)>,
                <NRF_PSEL(SPIM_MOSI, 0, 11)>,
                <NRF_PSEL(SPIM_MISO, 1, 9)>;
                
            low-power-enable;
        };
    };
    spi0_default: spi0_default {
        group1 {
            psels = <NRF_PSEL(SPIM_SCK, 0, 4)>,
                <NRF_PSEL(SPIM_MOSI, 0, 11)>;
        };
    };

    spi0_sleep: spi0_sleep {
        group1 {
            psels = <NRF_PSEL(SPIM_SCK, 0, 4)>,
                <NRF_PSEL(SPIM_MOSI, 0, 11)>;
            low-power-enable;
        };
    };
};


&spi1 {
    compatible = "nordic,nrf-spi";
    status = "okay";
    clock-frequency = <0x4000000>;
    overrun-character = < 255 >;
    cs-gpios = < &gpio0 5 GPIO_ACTIVE_LOW >;
};

&spi0 {
    compatible = "nordic,nrf-spi";
    status = "okay";
    clock-frequency = <0x4000000>;
    overrun-character = < 255 >;
    cs-gpios = < &gpio0 15 GPIO_ACTIVE_LOW >;
};

SPI Peripheral Power Consumption much higher than nrf5 SDK

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