From f1926ce63b996b42772b39e4b47bb4ef4ba748b4 Mon Sep 17 00:00:00 2001 From: Dominik Brodowski Date: Thu, 11 Sep 2008 11:09:49 +0200 Subject: [PATCH] clocksource, acpi_pm.c: fix check for monotonicity MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Actually check the monotonicity of the ACPI PMTMR ten times, only delay for 0.9 miliseconds at most, and bail out early if some problem is determined. Reported-by: Jochen Voß Signed-off-by: Dominik Brodowski Signed-off-by: Ingo Molnar --- drivers/clocksource/acpi_pm.c | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) diff --git a/drivers/clocksource/acpi_pm.c b/drivers/clocksource/acpi_pm.c index 4eee533f3f4a..71d2ac4e3f46 100644 --- a/drivers/clocksource/acpi_pm.c +++ b/drivers/clocksource/acpi_pm.c @@ -178,11 +178,13 @@ static int verify_pmtmr_rate(void) /* Number of monotonicity checks to perform during initialization */ #define ACPI_PM_MONOTONICITY_CHECKS 10 +/* Number of reads we try to get two different values */ +#define ACPI_PM_READ_CHECKS 10000 static int __init init_acpi_pm_clocksource(void) { cycle_t value1, value2; - unsigned int i, j, good = 0; + unsigned int i, j = 0; if (!pmtmr_ioport) return -ENODEV; @@ -192,29 +194,26 @@ static int __init init_acpi_pm_clocksource(void) /* "verify" this timing source: */ for (j = 0; j < ACPI_PM_MONOTONICITY_CHECKS; j++) { + udelay(100 * j); value1 = clocksource_acpi_pm.read(); - for (i = 0; i < 10000; i++) { + for (i = 0; i < ACPI_PM_READ_CHECKS; i++) { value2 = clocksource_acpi_pm.read(); if (value2 == value1) continue; if (value2 > value1) - good++; break; if ((value2 < value1) && ((value2) < 0xFFF)) - good++; break; printk(KERN_INFO "PM-Timer had inconsistent results:" " 0x%#llx, 0x%#llx - aborting.\n", value1, value2); return -EINVAL; } - udelay(300 * i); - } - - if (good != ACPI_PM_MONOTONICITY_CHECKS) { - printk(KERN_INFO "PM-Timer failed consistency check " - " (0x%#llx) - aborting.\n", value1); - return -ENODEV; + if (i == ACPI_PM_READ_CHECKS) { + printk(KERN_INFO "PM-Timer failed consistency check " + " (0x%#llx) - aborting.\n", value1); + return -ENODEV; + } } if (verify_pmtmr_rate() != 0) -- 2.20.1