# HG changeset patch
# User Mychaela Falconia <falcon@freecalypso.org>
# Date 1582765788 0
# Node ID f82551c77e586a8b11ac558018a169cafdd89514
# Parent  6824c4d5584890ab5495273754d7f8e26950b507
libserial-newlnx: ASYNC_LOW_LATENCY patch reverted

Reports from Das Signal indicate that loadtools performance on Debian
is about the same as on Slackware, and that including or omitting the
ASYNC_LOW_LATENCY patch from Serg makes no difference.  Because the
patch in question does not appear to be necessary, it is being reverted
until and unless someone other than Serg reports an actual real-world
system on which loadtools operation times are slowed compared to the
Mother's Slackware reference and on which Slackware-like performance
can be restored by setting the ASYNC_LOW_LATENCY flag.

diff -r 6824c4d55848 -r f82551c77e58 libserial-newlnx/openport.c
--- a/libserial-newlnx/openport.c	Tue Feb 25 18:40:00 2020 +0000
+++ b/libserial-newlnx/openport.c	Thu Feb 27 01:09:48 2020 +0000
@@ -5,7 +5,6 @@
 #include <sys/types.h>
 #include <sys/file.h>
 #include <sys/ioctl.h>
-#include <linux/serial.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -15,25 +14,11 @@
 open_serial_port(ttyport)
 	char *ttyport;
 {
-	struct serial_struct kernel_serial_settings;
-
 	target_fd = open(ttyport, O_RDWR|O_NONBLOCK);
 	if (target_fd < 0) {
 		perror(ttyport);
 		exit(1);
 	}
 	ioctl(target_fd, TIOCEXCL);
-	/*
-	 * It appears that some miscreants have modified recent Linux kernel
-	 * versions (newer than linux-4.4.14 of Slackware 14.2) to insert
-	 * a delay of 10 ms before select system call returns when serial
-	 * input is ready; this Linux kernel misbehaviour majorly slows down
-	 * many of our operations.  It appears that we need to set the
-	 * ASYNC_LOW_LATENCY flag in TIOCSSERIAL in order to get the old
-	 * sane behaviour back.
-	 */
-	ioctl(target_fd, TIOCGSERIAL, &kernel_serial_settings);
-	kernel_serial_settings.flags |= ASYNC_LOW_LATENCY;
-	ioctl(target_fd, TIOCSSERIAL, &kernel_serial_settings);
 	return 0;
 }