openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

failsafe mechanism to HPET clock calibration 

Provide a failsafe mechanism to avoid kernel spinning forever at
read_hpet_tsc during early kernel bootup.

This failsafe mechanism was originally introduced in commit
2f7a2a79c3, but looks like the hpet split
from time.c lost it again.

This reintroduces the failsafe mechanism

Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: Shai Fultheim <shai@scalex86.org>
Cc: Jack Steiner <steiner@sgi.com>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ravikiran G Thirumalai 2007-04-13 16:28:20 -07:00 committed by Linus Torvalds
parent ff99e40230
commit c9c57929d2
1 changed files with 6 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
arch/x86_64/kernel/hpet.c
View File

@ -191,6 +191,7 @@ int hpet_reenable(void)
#define TICK_COUNT 100000000
#define TICK_MIN 5000
#define MAX_TRIES 5
/*
* Some platforms take periodic SMI interrupts with 5ms duration. Make sure none
@ -198,13 +199,15 @@ int hpet_reenable(void)
*/
static void __init read_hpet_tsc(int *hpet, int *tsc)
{
int tsc1, tsc2, hpet1;
int tsc1, tsc2, hpet1, i;
do {
for (i = 0; i < MAX_TRIES; i++) {
tsc1 = get_cycles_sync();
hpet1 = hpet_readl(HPET_COUNTER);
tsc2 = get_cycles_sync();
} while (tsc2 - tsc1 > TICK_MIN);
if (tsc2 - tsc1 > TICK_MIN)
break;
}
*hpet = hpet1;
*tsc = tsc2;
}