[src/trunk]: src/sys/dev/acpi Improve a comment.

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

details:   https://anonhg.NetBSD.org/src/rev/792ebe847962
branches:  trunk
changeset: 768010:792ebe847962
user:      jruoho <jruoho%NetBSD.org@localhost>
date:      Sat Aug 06 13:19:46 2011 +0000

description:
Improve a comment.

diffstat:

 sys/dev/acpi/acpi_cpu_cstate.c |  14 +++++++++-----
 1 files changed, 9 insertions(+), 5 deletions(-)

diffs (35 lines):

diff -r 5c429baceddf -r 792ebe847962 sys/dev/acpi/acpi_cpu_cstate.c
--- a/sys/dev/acpi/acpi_cpu_cstate.c    Sat Aug 06 12:32:29 2011 +0000
+++ b/sys/dev/acpi/acpi_cpu_cstate.c    Sat Aug 06 13:19:46 2011 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: acpi_cpu_cstate.c,v 1.56 2011/08/05 02:29:53 mrg Exp $ */
+/* $NetBSD: acpi_cpu_cstate.c,v 1.57 2011/08/06 13:19:46 jruoho Exp $ */
 
 /*-
  * Copyright (c) 2010, 2011 Jukka Ruohonen <jruohonen%iki.fi@localhost>
@@ -27,7 +27,7 @@
  * SUCH DAMAGE.
  */
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: acpi_cpu_cstate.c,v 1.56 2011/08/05 02:29:53 mrg Exp $");
+__KERNEL_RCSID(0, "$NetBSD: acpi_cpu_cstate.c,v 1.57 2011/08/06 13:19:46 jruoho Exp $");
 
 #include <sys/param.h>
 #include <sys/cpu.h>
@@ -556,9 +556,13 @@
                cs[ACPI_STATE_C3].cs_method = 0;
 
        /*
-        * Sanity check the latency levels in FADT.
-        * Values above the thresholds are used to
-        * inform that C-states are not supported.
+        * Sanity check the latency levels in FADT. Values above
+        * the thresholds may be used to inform that C2 and C3 are
+        * not supported -- AMD family 11h is an example;
+        *
+        *      Advanced Micro Devices: BIOS and Kernel Developer's
+        *      Guide (BKDG) for AMD Family 11h Processors. Section
+        *      2.4.3, Revision 3.00, July, 2008.
         */
        CTASSERT(ACPICPU_C_C2_LATENCY_MAX == 100);
        CTASSERT(ACPICPU_C_C3_LATENCY_MAX == 1000);