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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:
parent
ff99e40230
commit
c9c57929d2
1 changed files with 6 additions and 3 deletions
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@ -191,6 +191,7 @@ int hpet_reenable(void)
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#define TICK_COUNT 100000000
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#define TICK_MIN 5000
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#define MAX_TRIES 5
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/*
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* Some platforms take periodic SMI interrupts with 5ms duration. Make sure none
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@ -198,13 +199,15 @@ int hpet_reenable(void)
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*/
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static void __init read_hpet_tsc(int *hpet, int *tsc)
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{
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int tsc1, tsc2, hpet1;
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int tsc1, tsc2, hpet1, i;
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do {
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for (i = 0; i < MAX_TRIES; i++) {
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tsc1 = get_cycles_sync();
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hpet1 = hpet_readl(HPET_COUNTER);
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tsc2 = get_cycles_sync();
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} while (tsc2 - tsc1 > TICK_MIN);
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if (tsc2 - tsc1 > TICK_MIN)
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break;
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}
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*hpet = hpet1;
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*tsc = tsc2;
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}
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