projects / people / pmueller / ipfire-2.x.git / blame
| Commit | Line | Data |
|---|---|---|
| 00e5a55c BS |
1 | From: john stultz <johnstul@us.ibm.com> |
| 2 | Date: Fri, 13 Feb 2009 02:48:53 +0000 (-0800) | |
| 3 | Subject: x86, hpet: fix for LS21 + HPET = boot hang | |
| 4 | Patch-mainline: 2.6.29-rc6 | |
| 5 | Git-commit: b13e24644c138d0ddbc451403c30a96b09bfd556 | |
| 6 | References: bnc#476877 | |
| 7 | ||
| 8 | x86, hpet: fix for LS21 + HPET = boot hang | |
| 9 | ||
| 10 | Between 2.6.23 and 2.6.24-rc1 a change was made that broke IBM LS21 | |
| 11 | systems that had the HPET enabled in the BIOS, resulting in boot hangs | |
| 12 | for x86_64. | |
| 13 | ||
| 14 | Specifically commit b8ce33590687888ebb900d09557b8807c4539022, which | |
| 15 | merges the i386 and x86_64 HPET code. | |
| 16 | ||
| 17 | Prior to this commit, when we setup the HPET timers in x86_64, we did | |
| 18 | the following: | |
| 19 | ||
| 20 | hpet_writel(HPET_TN_ENABLE | HPET_TN_PERIODIC | HPET_TN_SETVAL | | |
| 21 | HPET_TN_32BIT, HPET_T0_CFG); | |
| 22 | ||
| 23 | However after the i386/x86_64 HPET merge, we do the following: | |
| 24 | ||
| 25 | cfg = hpet_readl(HPET_Tn_CFG(timer)); | |
| 26 | cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC | | |
| 27 | HPET_TN_SETVAL | HPET_TN_32BIT; | |
| 28 | hpet_writel(cfg, HPET_Tn_CFG(timer)); | |
| 29 | ||
| 30 | However on LS21s with HPET enabled in the BIOS, the HPET_T0_CFG register | |
| 31 | boots with Level triggered interrupts (HPET_TN_LEVEL) enabled. This | |
| 32 | causes the periodic interrupt to be not so periodic, and that results in | |
| 33 | the boot time hang I reported earlier in the delay calibration. | |
| 34 | ||
| 35 | My fix: Always disable HPET_TN_LEVEL when setting up periodic mode. | |
| 36 | ||
| 37 | Signed-off-by: John Stultz <johnstul@us.ibm.com> | |
| 38 | Signed-off-by: Ingo Molnar <mingo@elte.hu> | |
| 39 | Acked-by: Jeff Mahoney <jeffm@suse.com> | |
| 40 | --- | |
| 41 | ||
| 42 | --- | |
| 43 | arch/x86/kernel/hpet.c | 2 ++ | |
| 44 | 1 file changed, 2 insertions(+) | |
| 45 | ||
| 46 | --- a/arch/x86/kernel/hpet.c | |
| 47 | +++ b/arch/x86/kernel/hpet.c | |
| 48 | @@ -304,6 +304,8 @@ static void hpet_legacy_set_mode(enum cl | |
| 49 | now = hpet_read_value(HPET_COUNTER); | |
| 50 | cmp = now + (unsigned long) delta; | |
| 51 | cfg = hpet_readl(HPET_T0_CFG); | |
| 52 | + /* Make sure we use edge triggered interrupts */ | |
| 53 | + cfg &= ~HPET_TN_LEVEL; | |
| 54 | cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC | | |
| 55 | HPET_TN_SETVAL | | |
| 56 | (hpet_legacy_use_64_bits ? 0 : HPET_TN_32BIT); |