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author | James Morris <jmorris@namei.org> | 2008-08-28 10:47:34 +1000 |
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committer | James Morris <jmorris@namei.org> | 2008-08-28 10:47:34 +1000 |
commit | 86d688984deefa3ae5a802880c11f2b408b5d6cf (patch) | |
tree | 7ea5e8189b0a774626d3ed7c3c87df2495a4c4a0 /arch/x86/kernel/hpet.c | |
parent | 93c06cbbf9fea5d5be1778febb7fa9ab1a74e5f5 (diff) | |
parent | 4c246edd2550304df5b766cc841584b2bb058843 (diff) | |
download | op-kernel-dev-86d688984deefa3ae5a802880c11f2b408b5d6cf.zip op-kernel-dev-86d688984deefa3ae5a802880c11f2b408b5d6cf.tar.gz |
Merge branch 'master' into next
Diffstat (limited to 'arch/x86/kernel/hpet.c')
-rw-r--r-- | arch/x86/kernel/hpet.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c index ad2b15a..59fd3b6 100644 --- a/arch/x86/kernel/hpet.c +++ b/arch/x86/kernel/hpet.c @@ -359,6 +359,7 @@ static int hpet_clocksource_register(void) int __init hpet_enable(void) { unsigned long id; + int i; if (!is_hpet_capable()) return 0; @@ -369,6 +370,29 @@ int __init hpet_enable(void) * Read the period and check for a sane value: */ hpet_period = hpet_readl(HPET_PERIOD); + + /* + * AMD SB700 based systems with spread spectrum enabled use a + * SMM based HPET emulation to provide proper frequency + * setting. The SMM code is initialized with the first HPET + * register access and takes some time to complete. During + * this time the config register reads 0xffffffff. We check + * for max. 1000 loops whether the config register reads a non + * 0xffffffff value to make sure that HPET is up and running + * before we go further. A counting loop is safe, as the HPET + * access takes thousands of CPU cycles. On non SB700 based + * machines this check is only done once and has no side + * effects. + */ + for (i = 0; hpet_readl(HPET_CFG) == 0xFFFFFFFF; i++) { + if (i == 1000) { + printk(KERN_WARNING + "HPET config register value = 0xFFFFFFFF. " + "Disabling HPET\n"); + goto out_nohpet; + } + } + if (hpet_period < HPET_MIN_PERIOD || hpet_period > HPET_MAX_PERIOD) goto out_nohpet; |