clocksource, acpi_pm.c: fix check for monotonicity
authorDominik Brodowski <linux@dominikbrodowski.net>
Thu, 11 Sep 2008 09:09:49 +0000 (11:09 +0200)
committerIngo Molnar <mingo@elte.hu>
Thu, 11 Sep 2008 09:14:29 +0000 (11:14 +0200)
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 <jochen.voss@googlemail.com>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
drivers/clocksource/acpi_pm.c

index 4eee533f3f4af7e8f5c9d811c7ac671d95d05083..71d2ac4e3f46cc0e33410a2d8f7889ac1ae8de09 100644 (file)
@@ -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)