[src/trunk]: src/sys/arch/evbarm/dev plcom: speed up close with HUPCL set

[jmcneill <jmcneill%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/ec1dc1164529
branches:  trunk
changeset: 1024311:ec1dc1164529
user:      jmcneill <jmcneill%NetBSD.org@localhost>
date:      Sun Oct 17 22:34:17 2021 +0000

description:
plcom: speed up close with HUPCL set

Instead of incurring a 1s penalty on close of a plcom device with HUPCL set,
defer the sleep until the next open, and only sleep if necessary.

diffstat:

 sys/arch/evbarm/dev/plcom.c    |  23 +++++++++++++++++------
 sys/arch/evbarm/dev/plcomvar.h |   4 +++-
 2 files changed, 20 insertions(+), 7 deletions(-)

diffs (76 lines):

diff -r 5ee6419cd708 -r ec1dc1164529 sys/arch/evbarm/dev/plcom.c
--- a/sys/arch/evbarm/dev/plcom.c       Sun Oct 17 20:40:20 2021 +0000
+++ b/sys/arch/evbarm/dev/plcom.c       Sun Oct 17 22:34:17 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: plcom.c,v 1.62 2020/10/19 17:00:02 tnn Exp $   */
+/*     $NetBSD: plcom.c,v 1.63 2021/10/17 22:34:17 jmcneill Exp $      */
 
 /*-
  * Copyright (c) 2001 ARM Ltd
@@ -94,7 +94,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: plcom.c,v 1.62 2020/10/19 17:00:02 tnn Exp $");
+__KERNEL_RCSID(0, "$NetBSD: plcom.c,v 1.63 2021/10/17 22:34:17 jmcneill Exp $");
 
 #include "opt_plcom.h"
 #include "opt_ddb.h"
@@ -686,10 +686,8 @@
         */
        if (ISSET(tp->t_cflag, HUPCL)) {
                plcom_modem(sc, 0);
-               mutex_spin_exit(&sc->sc_lock);
-               /* XXX will only timeout */
-               (void) kpause(ttclos, false, hz, NULL);
-               mutex_spin_enter(&sc->sc_lock);
+               microtime(&sc->sc_hup_pending);
+               sc->sc_hup_pending.tv_sec++;
        }
 
        sc->sc_cr = 0;
@@ -773,6 +771,7 @@
         */
        if (!ISSET(tp->t_state, TS_ISOPEN) && tp->t_wopen == 0) {
                struct termios t;
+               struct timeval now, diff;
 
                tp->t_dev = dev;
 
@@ -790,6 +789,18 @@
                        mutex_spin_enter(&sc->sc_lock);
                }
 
+               if (timerisset(&sc->sc_hup_pending)) {
+                       microtime(&now);
+                       while (timercmp(&now, &sc->sc_hup_pending, <)) {
+                               timersub(&sc->sc_hup_pending, &now, &diff);
+                               const int ms = diff.tv_sec * 100 +
+                                   uimax(diff.tv_usec / 1000, 1);
+                               kpause(ttclos, false, mstohz(ms), &sc->sc_lock);
+                               microtime(&now);
+                       }
+                       timerclear(&sc->sc_hup_pending);
+               }
+
                /* Turn on interrupts. */
                /* IER_ERXRDY | IER_ERLS | IER_EMSC;  */
                /* Fetch the current modem control status, needed later. */
diff -r 5ee6419cd708 -r ec1dc1164529 sys/arch/evbarm/dev/plcomvar.h
--- a/sys/arch/evbarm/dev/plcomvar.h    Sun Oct 17 20:40:20 2021 +0000
+++ b/sys/arch/evbarm/dev/plcomvar.h    Sun Oct 17 22:34:17 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: plcomvar.h,v 1.17 2017/10/12 20:05:42 skrll Exp $      */
+/*     $NetBSD: plcomvar.h,v 1.18 2021/10/17 22:34:17 jmcneill Exp $   */
 
 /*
  * Copyright (c) 1996 Christopher G. Demetriou.  All rights reserved.
@@ -104,6 +104,8 @@
            sc_swflags;
        u_int sc_fifolen;
 
+       struct timeval sc_hup_pending;
+
        u_int sc_r_hiwat,
              sc_r_lowat;
        u_char *volatile sc_rbget,