[src/trunk]: src/sys/dev/ic For the DW APB busy bit workaround, only attempt ...

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

details:   https://anonhg.NetBSD.org/src/rev/cdaf1262a8e8
branches:  trunk
changeset: 1024649:cdaf1262a8e8
user:      jmcneill <jmcneill%NetBSD.org@localhost>
date:      Sat Oct 30 11:43:17 2021 +0000

description:
For the DW APB busy bit workaround, only attempt to re-apply LCR and DLB
settings for non-console devices. In the console case, simply clear the
busy bit and continue. Fixes an interrupt storm observed on Macchiatobin.

diffstat:

 sys/dev/ic/com.c |  8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)

diffs (29 lines):

diff -r 331c17797a8d -r cdaf1262a8e8 sys/dev/ic/com.c
--- a/sys/dev/ic/com.c  Sat Oct 30 11:41:49 2021 +0000
+++ b/sys/dev/ic/com.c  Sat Oct 30 11:43:17 2021 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: com.c,v 1.371 2021/10/21 10:22:54 jmcneill Exp $ */
+/* $NetBSD: com.c,v 1.372 2021/10/30 11:43:17 jmcneill Exp $ */
 
 /*-
  * Copyright (c) 1998, 1999, 2004, 2008 The NetBSD Foundation, Inc.
@@ -66,7 +66,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: com.c,v 1.371 2021/10/21 10:22:54 jmcneill Exp $");
+__KERNEL_RCSID(0, "$NetBSD: com.c,v 1.372 2021/10/30 11:43:17 jmcneill Exp $");
 
 #include "opt_com.h"
 #include "opt_ddb.h"
@@ -2147,7 +2147,9 @@
        /* DesignWare APB UART BUSY interrupt */
        if (sc->sc_type == COM_TYPE_DW_APB &&
            (iir & IIR_BUSY) == IIR_BUSY) {
-               if ((CSR_READ_1(regsp, COM_REG_USR) & 0x1) != 0) {
+               if (ISSET(sc->sc_hwflags, COM_HW_CONSOLE)) {
+                       (void)CSR_READ_1(regsp, COM_REG_USR);
+               } else if ((CSR_READ_1(regsp, COM_REG_USR) & 0x1) != 0) {
                        CSR_WRITE_1(regsp, COM_REG_HALT, HALT_CHCFG_EN);
                        CSR_WRITE_1(regsp, COM_REG_LCR, sc->sc_lcr | LCR_DLAB);
                        CSR_WRITE_1(regsp, COM_REG_DLBL, sc->sc_dlbl);