Module Name: src
Committed By: jmcneill
Date: Sun Jul 25 01:43:08 UTC 2021
Modified Files:
src/sys/dev/acpi: acpi_timer.c
Log Message:
acpi_timer: use ACPI-Fast if WAET timer one read flag is set
The Windows ACPI Emulated Devices Table (WAET) has a hint to inform the OS
that a single read of the PM timer is reliable. Honour this flag.
To generate a diff of this commit:
cvs rdiff -u -r1.26 -r1.27 src/sys/dev/acpi/acpi_timer.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/dev/acpi/acpi_timer.c
diff -u src/sys/dev/acpi/acpi_timer.c:1.26 src/sys/dev/acpi/acpi_timer.c:1.27
--- src/sys/dev/acpi/acpi_timer.c:1.26 Fri May 29 12:30:41 2020
+++ src/sys/dev/acpi/acpi_timer.c Sun Jul 25 01:43:08 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: acpi_timer.c,v 1.26 2020/05/29 12:30:41 rin Exp $ */
+/* $NetBSD: acpi_timer.c,v 1.27 2021/07/25 01:43:08 jmcneill Exp $ */
/*-
* Copyright (c) 2006 Matthias Drochner <[email protected]>
@@ -27,7 +27,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: acpi_timer.c,v 1.26 2020/05/29 12:30:41 rin Exp $");
+__KERNEL_RCSID(0, "$NetBSD: acpi_timer.c,v 1.27 2021/07/25 01:43:08 jmcneill Exp $");
#include <sys/types.h>
#include <sys/systm.h>
@@ -61,6 +61,7 @@ int
acpitimer_init(struct acpi_softc *sc)
{
#if (!ACPI_REDUCED_HARDWARE)
+ ACPI_TABLE_WAET *waet;
ACPI_STATUS rv;
uint32_t bits;
int i, j;
@@ -79,6 +80,18 @@ acpitimer_init(struct acpi_softc *sc)
for (i = j = 0; i < 10; i++)
j += acpitimer_test();
+ rv = AcpiGetTable(ACPI_SIG_WAET, 0, (ACPI_TABLE_HEADER **)&waet);
+ if (ACPI_SUCCESS(rv)) {
+ /*
+ * Windows ACPI Emulated Devices Table (WAET) has a hint
+ * to let the OS know that a single read of the PM timer
+ * provides a reliable value.
+ */
+ if ((waet->Flags & ACPI_WAET_TIMER_ONE_READ) != 0) {
+ j += 10;
+ }
+ }
+
if (j >= 10) {
acpi_timecounter.tc_name = "ACPI-Fast";
acpi_timecounter.tc_get_timecount = acpitimer_read_fast;
