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clocksource, acpi_pm.c: use proper read function also in errata mode

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On all hardware (some Intel ICH4, PIIX4 and PIIX4E chipsets) affected by a
hardware errata there's about a 4.2% chance that initialization of the
ACPI PMTMR fails.  On those chipsets, we need to read out the timer value
at least three times to get a correct result, for every once in a while
(i.e.  within a 3 ns window every 69.8 ns) the read returns a bogus
result.  During normal operation we work around this issue, but during
initialization reading a bogus value may lead to -EINVAL even though the
hardware is usable.

Thanks to Andreas Mohr for spotting this issue.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Dominik Brodowski 2008-09-05 14:05:33 -07:00 committed by Ingo Molnar
parent 4ff4b9e19a
commit dfdf748a61
1 changed files with 8 additions and 8 deletions
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16
drivers/clocksource/acpi_pm.c
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@ -151,13 +151,13 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, PCI_DEVICE_ID_SERVERWORKS_LE,
*/
static int verify_pmtmr_rate(void)
{
u32 value1, value2;
cycle_t value1, value2;
unsigned long count, delta;
mach_prepare_counter();
value1 = read_pmtmr();
value1 = clocksource_acpi_pm.read();
mach_countup(&count);
value2 = read_pmtmr();
value2 = clocksource_acpi_pm.read();
delta = (value2 - value1) & ACPI_PM_MASK;
/* Check that the PMTMR delta is within 5% of what we expect */
@ -177,7 +177,7 @@ static int verify_pmtmr_rate(void)
static int __init init_acpi_pm_clocksource(void)
{
u32 value1, value2;
cycle_t value1, value2;
unsigned int i;
if (!pmtmr_ioport)
@ -187,9 +187,9 @@ static int __init init_acpi_pm_clocksource(void)
clocksource_acpi_pm.shift);
/* "verify" this timing source: */
value1 = read_pmtmr();
value1 = clocksource_acpi_pm.read();
for (i = 0; i < 10000; i++) {
value2 = read_pmtmr();
value2 = clocksource_acpi_pm.read();
if (value2 == value1)
continue;
if (value2 > value1)
@ -197,11 +197,11 @@ static int __init init_acpi_pm_clocksource(void)
if ((value2 < value1) && ((value2) < 0xFFF))
goto pm_good;
printk(KERN_INFO "PM-Timer had inconsistent results:"
" 0x%#x, 0x%#x - aborting.\n", value1, value2);
" 0x%#llx, 0x%#llx - aborting.\n", value1, value2);
return -EINVAL;
}
printk(KERN_INFO "PM-Timer had no reasonable result:"
" 0x%#x - aborting.\n", value1);
" 0x%#llx - aborting.\n", value1);
return -ENODEV;
pm_good: