From: Michael Chang <mchang@suse.com>
Date: Tue, 1 Dec 2015 15:49:38 +0000 (+0300)
Subject: i386: fix TSC calibration using PIT
X-Git-Tag: 2.02-beta3~162
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a03c1034f6062e69075056c8f31b90e159ce5244;p=thirdparty%2Fgrub.git

i386: fix TSC calibration using PIT

Condition was accidentally reversed, so PIT calibration always failed
when PIT was present and always succeeded when PIT was missing, but in
the latter case resulted in absurdly fast clock.

Reported and tested by Vitaly Kuznetsov <vkuznets@redhat.com>
---

diff --git a/grub-core/kern/i386/tsc_pit.c b/grub-core/kern/i386/tsc_pit.c
index 0c0488c1b..67990bfa6 100644
--- a/grub-core/kern/i386/tsc_pit.c
+++ b/grub-core/kern/i386/tsc_pit.c
@@ -49,7 +49,7 @@ grub_pit_wait (void)
 	     | GRUB_PIT_SPK_TMR2,
              GRUB_PIT_SPEAKER_PORT);
 
-  if ((grub_inb (GRUB_PIT_SPEAKER_PORT) & GRUB_PIT_SPK_TMR2_LATCH)) {
+  if ((grub_inb (GRUB_PIT_SPEAKER_PORT) & GRUB_PIT_SPK_TMR2_LATCH) == 0x00) {
     ret = 1;
     /* Wait.  */
     while ((grub_inb (GRUB_PIT_SPEAKER_PORT) & GRUB_PIT_SPK_TMR2_LATCH) == 0x00);