Fixed the SMC fifo bug fix. sioopen() hung while input was streaming in

with <= 100 usec between each character arrival time.  This didn't happen
until rev.1.75 of clock.c because DELAY(100) used to delay for closer to
80 usec than 100 usec, and the minimum time between character arrivals is
87.8 usec at the maximum supported speed of 115200 bps 8N1.

Clear DCD timestamp flag on close (the input timestamp flag is already
cleared).

1 files changed, 15 insertions, 3 deletions

diff --git a/sys/dev/sio/sio.c b/sys/dev/sio/sio.c
index 1f09168..a9de446 100644
--- a/sys/dev/sio/sio.c
+++ b/sys/dev/sio/sio.c
@@ -1078,11 +1078,22 @@ open_top:
 				outb(iobase + com_fifo,
 				     FIFO_RCV_RST | FIFO_XMT_RST
 				     | com->fifo_image);
-				DELAY(100);
+				/*
+				 * XXX the delays are for superstitious
+				 * historical reasons.  It must be less than
+				 * the character time at the maximum
+				 * supported speed (87 usec at 115200 bps
+				 * 8N1).  Otherwise we might loop endlessly
+				 * if data is streaming in.  We used to use
+				 * delays of 100.  That usually worked
+				 * because DELAY(100) used to usually delay
+				 * for about 85 usec instead of 100.
+				 */
+				DELAY(50);
 				if (!(inb(com->line_status_port) & LSR_RXRDY))
 					break;
 				outb(iobase + com_fifo, 0);
-				DELAY(100);
+				DELAY(50);
 				(void) inb(com->data_port);
 			}
 		}
@@ -1188,7 +1199,8 @@ comhardclose(com)
 	s = spltty();
 	com->poll = FALSE;
 	com->poll_output = FALSE;
-	com->do_timestamp = 0;
+	com->do_timestamp = FALSE;
+	com->do_dcd_timestamp = FALSE;
 	outb(iobase + com_cfcr, com->cfcr_image &= ~CFCR_SBREAK);
 	{
 		outb(iobase + com_ier, 0);