diff options
| author | john stultz <johnstul@us.ibm.com> | 2009-02-12 18:48:53 -0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-02-13 09:15:46 +0100 |
| commit | b13e24644c138d0ddbc451403c30a96b09bfd556 (patch) | |
| tree | 5ce9c5d1885c78bee5da87fe2cd0d4fb0efccbf2 /arch/x86/kernel/hpet.c | |
| parent | 7ad9de6ac83bd825996d2de98c92e0f425c31050 (diff) | |
x86, hpet: fix for LS21 + HPET = boot hang
Between 2.6.23 and 2.6.24-rc1 a change was made that broke IBM LS21
systems that had the HPET enabled in the BIOS, resulting in boot hangs
for x86_64.
Specifically commit b8ce33590687888ebb900d09557b8807c4539022, which
merges the i386 and x86_64 HPET code.
Prior to this commit, when we setup the HPET timers in x86_64, we did
the following:
hpet_writel(HPET_TN_ENABLE | HPET_TN_PERIODIC | HPET_TN_SETVAL |
HPET_TN_32BIT, HPET_T0_CFG);
However after the i386/x86_64 HPET merge, we do the following:
cfg = hpet_readl(HPET_Tn_CFG(timer));
cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC |
HPET_TN_SETVAL | HPET_TN_32BIT;
hpet_writel(cfg, HPET_Tn_CFG(timer));
However on LS21s with HPET enabled in the BIOS, the HPET_T0_CFG register
boots with Level triggered interrupts (HPET_TN_LEVEL) enabled. This
causes the periodic interrupt to be not so periodic, and that results in
the boot time hang I reported earlier in the delay calibration.
My fix: Always disable HPET_TN_LEVEL when setting up periodic mode.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/hpet.c')
| -rw-r--r-- | arch/x86/kernel/hpet.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c index 64d5ad0b8add..5c8da2c2c185 100644 --- a/arch/x86/kernel/hpet.c +++ b/arch/x86/kernel/hpet.c @@ -269,6 +269,8 @@ static void hpet_set_mode(enum clock_event_mode mode, now = hpet_readl(HPET_COUNTER); cmp = now + (unsigned long) delta; cfg = hpet_readl(HPET_Tn_CFG(timer)); + /* Make sure we use edge triggered interrupts */ + cfg &= ~HPET_TN_LEVEL; cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC | HPET_TN_SETVAL | HPET_TN_32BIT; hpet_writel(cfg, HPET_Tn_CFG(timer)); |