Re: [PATCH] tty: serial: uartlite: Specify time for sending chars

[Peter Korsgaard]

>>>>> "Michal" == Michal Simek <michal.simek@xxxxxxxxxx> writes:

 > Xilinx MDM (Microblaze Debug Module) also contains
 > uart interface via JTAG which is compatible with
 > uartlite driver. This interface is really slow
 > that's why timeout is setup to 1s.

 > Make this time delay not to be cpu speed dependent.

 > Signed-off-by: Michal Simek <michal.simek@xxxxxxxxxx>
 > ---

 > RFC sent here:
 > https://lkml.org/lkml/2013/9/30/250
 > I finally got HW design which is just slow to be able
 > to test it.

 > ---
 >  drivers/tty/serial/uartlite.c | 10 ++++++++--
 >  1 file changed, 8 insertions(+), 2 deletions(-)

 > diff --git a/drivers/tty/serial/uartlite.c b/drivers/tty/serial/uartlite.c
 > index 5f90ef24d475..723a6b79cd14 100644
 > --- a/drivers/tty/serial/uartlite.c
 > +++ b/drivers/tty/serial/uartlite.c
 > @@ -418,14 +418,20 @@ static struct uart_ops ulite_ops = {
 >  #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
 >  static void ulite_console_wait_tx(struct uart_port *port)
 >  {
 > -	int i;
 >  	u8 val;
 > +	unsigned long timeout;

 >  	/* Spin waiting for TX fifo to have space available */
 > -	for (i = 0; i < 100000; i++) {

It would be good to add a note about the slow jtag variant here.

Otherwise:

Acked-by: Peter Korsgaard <peter@xxxxxxxxxxxxx>

 > +	timeout = jiffies + msecs_to_jiffies(1000);
 > +	while (1) {
 >  		val = uart_in32(ULITE_STATUS, port);
 >  		if ((val & ULITE_STATUS_TXFULL) == 0)
 >  			break;
 > +		if (time_after(jiffies, timeout)) {
 > +			dev_warn(port->dev,
 > +				 "timeout waiting for TX buffer empty\n");
 > +			break;
 > +		}
 >  		cpu_relax();
 >  	}
 >  }
 > --
 > 1.8.2.3


-- 
Bye, Peter Korsgaard
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