serial: 8250: Don't delay after transmitter is ready.

The loop in wait_for_xmitr() is delaying one extra uS after the ready
condition has been met.  Rewrite the loop to only delay if the
transmitter is not ready.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 24110f6f61e0..31b8cca179cd 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -1867,15 +1867,17 @@ static void wait_for_xmitr(struct uart_8250_port *up, int bits)
         unsigned int status, tmout = 10000;
 
         /* Wait up to 10ms for the character(s) to be sent. */
-        do {
+        for (;;) {
                 status = serial_in(up, UART_LSR);
 
                 up->lsr_saved_flags |= status & LSR_SAVE_FLAGS;
 
+                if ((status & bits) == bits)
+                        break;
                 if (--tmout == 0)
                         break;
                 udelay(1);
-        } while ((status & bits) != bits);
+        }
 
         /* Wait up to 1s for flow control if necessary */
         if (up->port.flags & UPF_CONS_FLOW) {