spi fails after removing print statements

[faikab]

So i am utilizing SPI and i got it to work, however for some absurd reason after removing the segger_print statement below from before the while loop the spi would stop functioning. otherwise it works perfectly fine. Any idea why a print statement would cause this? do i need to add a delay? Although i would expect the while loop to handle any delay necessary.

uint32_t LCD_SPI_Write_Command (uint8_t command)
{
	spi_lcd_xfer_done = false;
	LCD_CSX_LOW(); //	set CSX to low to activate LCD listening
	LCD_DCX_LOW(); // indicate command
	uint32_t err_code = nrf_drv_spi_transfer(&m_spi_LCD, &command, 1, NULL, 0);
	if (err_code != NRF_SUCCESS) {
		SEGGER_RTT_printf(0, "[ERROR] on command transfer :%d \n", err_code);
	}
		SEGGER_RTT_printf(0,"Im writing a command! \n");

	while (!spi_lcd_xfer_done)
	  {
	  }
	return err_code;
}

[kl-cruz]

I assume that spi_lcd_xfer_done is setting to true in interrupt routine or callback. Has it volatile keyword?

[faikab]

it is set in true as follows, but not volatile just to be clear everything is working in code above. however it stops working when the the SEGGER_RTT line which prints "Im writing a command" is commented out/deleted

static bool spi_lcd_xfer_done = false;

/**
 * @brief SPI user event handler.
 * @param event
 */
void spi_lcd_event_handler(nrf_drv_spi_evt_t const * p_event)
{
	spi_lcd_xfer_done = true;
	switch(p_event->type)
		{
		case NRF_DRV_SPI_EVENT_DONE:
		    printf(" Transfer completed.\r\n");
			break;
		default:
			break;
		}
}