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>
*/
static int verify_pmtmr_rate(void)
{
*/
static int verify_pmtmr_rate(void)
{
+ cycle_t value1, value2;
unsigned long count, delta;
mach_prepare_counter();
unsigned long count, delta;
mach_prepare_counter();
+ value1 = clocksource_acpi_pm.read();
+ value2 = clocksource_acpi_pm.read();
delta = (value2 - value1) & ACPI_PM_MASK;
/* Check that the PMTMR delta is within 5% of what we expect */
delta = (value2 - value1) & ACPI_PM_MASK;
/* Check that the PMTMR delta is within 5% of what we expect */
static int __init init_acpi_pm_clocksource(void)
{
static int __init init_acpi_pm_clocksource(void)
{
+ cycle_t value1, value2;
unsigned int i;
if (!pmtmr_ioport)
unsigned int i;
if (!pmtmr_ioport)
clocksource_acpi_pm.shift);
/* "verify" this timing source: */
clocksource_acpi_pm.shift);
/* "verify" this timing source: */
+ value1 = clocksource_acpi_pm.read();
for (i = 0; i < 10000; i++) {
for (i = 0; i < 10000; i++) {
+ value2 = clocksource_acpi_pm.read();
if (value2 == value1)
continue;
if (value2 > value1)
if (value2 == value1)
continue;
if (value2 > value1)
if ((value2 < value1) && ((value2) < 0xFFF))
goto pm_good;
printk(KERN_INFO "PM-Timer had inconsistent results:"
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:"
return -EINVAL;
}
printk(KERN_INFO "PM-Timer had no reasonable result:"
- " 0x%#x - aborting.\n", value1);
+ " 0x%#llx - aborting.\n", value1);