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;
}

[faikab]

thanks kl-cruz it actually worked. i still dont fully understand why the elimination of a comment would prevent it from working and simply adding the keyword volatile would permit it to work again.

as for your other recommendation, i didnt fully understand it. I dont have a thread or OS. simply one main method. but i guess what you are recommending is to do something similar to this right?

if (spi_lcd_xfer_done ==true) {
      nrf_drv_spi_transfer();
}

so it wont send data unless transfer is done and that way it wont wait at while loop right?

[kl-cruz]

It is not needed to load it everytime from RAM memory. In the end variable will be updated, but without volatile keyword You worked on local copy. RTT functions adding and removing - Compiler probably was lack of available registers and do writing/reading operations. That's why it worked. So You are lucky one.