drivers/tty/serial/mvebu-uart.c:605 mvebu_uart_putc() warn: this loop depends on readl() succeeding

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   449dc8c97089a6e09fb2dac4d92b1b7ac0eb7c1e
commit: 05933aac7b11911955de307a329dc2a7a14b7bd0 ia64: remove now unused machvec indirections
date:   12 months ago
config: ia64-randconfig-m031-20200808 (attached as .config)
compiler: ia64-linux-gcc (GCC) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

New smatch warnings:
drivers/tty/serial/mvebu-uart.c:605 mvebu_uart_putc() warn: this loop depends on readl() succeeding

Old smatch warnings:
drivers/tty/serial/mvebu-uart.c:293 mvebu_uart_rx_chars() warn: this loop depends on readl() succeeding

vim +605 drivers/tty/serial/mvebu-uart.c

30530791a7a032 Wilson Ding   2016-02-16  595  
30530791a7a032 Wilson Ding   2016-02-16  596  #ifdef CONFIG_SERIAL_MVEBU_CONSOLE
30530791a7a032 Wilson Ding   2016-02-16  597  /* Early Console */
30530791a7a032 Wilson Ding   2016-02-16  598  static void mvebu_uart_putc(struct uart_port *port, int c)
30530791a7a032 Wilson Ding   2016-02-16  599  {
30530791a7a032 Wilson Ding   2016-02-16  600  	unsigned int st;
30530791a7a032 Wilson Ding   2016-02-16  601  
30530791a7a032 Wilson Ding   2016-02-16  602  	for (;;) {
30530791a7a032 Wilson Ding   2016-02-16  603  		st = readl(port->membase + UART_STAT);
30530791a7a032 Wilson Ding   2016-02-16  604  		if (!(st & STAT_TX_FIFO_FUL))
30530791a7a032 Wilson Ding   2016-02-16 @605  			break;
30530791a7a032 Wilson Ding   2016-02-16  606  	}
30530791a7a032 Wilson Ding   2016-02-16  607  
5218d76958644a Miquel Raynal 2017-10-13  608  	/* At early stage, DT is not parsed yet, only use UART0 */
5218d76958644a Miquel Raynal 2017-10-13  609  	writel(c, port->membase + UART_STD_TSH);
30530791a7a032 Wilson Ding   2016-02-16  610  
30530791a7a032 Wilson Ding   2016-02-16  611  	for (;;) {
30530791a7a032 Wilson Ding   2016-02-16  612  		st = readl(port->membase + UART_STAT);
30530791a7a032 Wilson Ding   2016-02-16  613  		if (st & STAT_TX_FIFO_EMP)
30530791a7a032 Wilson Ding   2016-02-16  614  			break;
30530791a7a032 Wilson Ding   2016-02-16  615  	}
30530791a7a032 Wilson Ding   2016-02-16  616  }
30530791a7a032 Wilson Ding   2016-02-16  617  

:::::: The code at line 605 was first introduced by commit
:::::: 30530791a7a032dc27dbbab56b8afabd5138074c serial: mvebu-uart: initial support for Armada-3700 serial port

:::::: TO: Wilson Ding <dingwei@xxxxxxxxxxx>
:::::: CC: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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