[haiku-commits] r41678 - haiku/trunk/src/system/boot/platform/bios_ia32

From: mmlr@xxxxxxxx
To: haiku-commits@xxxxxxxxxxxxx
Date: Mon, 23 May 2011 14:36:43 +0200 (CEST)
Author: mmlr
Date: 2011-05-23 14:36:43 +0200 (Mon, 23 May 2011)
New Revision: 41678
Changeset: https://dev.haiku-os.org/changeset/41678

Modified:
   haiku/trunk/src/system/boot/platform/bios_ia32/cpu.cpp
Log:
* Add a limit to how often we retry the calibration. It's there as an upper
  bound to prevent spinning forever if we have a very unstable TSC that we
  simply can't calibrate. Shouldn't really happen though.
* Set the gate low for channel 2 on exit if we used it as the counter.


Modified: haiku/trunk/src/system/boot/platform/bios_ia32/cpu.cpp
===================================================================
--- haiku/trunk/src/system/boot/platform/bios_ia32/cpu.cpp      2011-05-23 
12:33:51 UTC (rev 41677)
+++ haiku/trunk/src/system/boot/platform/bios_ia32/cpu.cpp      2011-05-23 
12:36:43 UTC (rev 41678)
@@ -68,6 +68,13 @@
 #define PIT_CHANNEL_2_SPEAKER_OFF_MASK ~0x02
 
 
+// Maximum values
+#define MAX_QUICK_SAMPLES                              20
+#define MAX_SLOW_SAMPLES                               20
+       // TODO: These are arbitrary. They are here to avoid spinning 
indefinitely
+       // if the TSC just isn't stable and we can't get our desired error 
range.
+
+
 #define CPUID_EFLAGS   (1UL << 21)
 #define RDTSC_FEATURE  (1UL << 4)
 
@@ -238,6 +245,9 @@
        double conversionFactorQuick, conversionFactorSlower, 
conversionFactorSlow;
        uint16 expired;
 
+       uint32 quickSampleCount = 1;
+       uint32 slowSampleCount = 1;
+
 quick_sample:
        calibration_loop(224, channel, tscDeltaQuick, conversionFactorQuick,
                expired);
@@ -249,7 +259,8 @@
        double deviation = conversionFactorQuick / conversionFactorSlower;
        if (deviation < 0.99 || deviation > 1.01) {
                // We might have been hit by a SMI or were otherwise stalled
-               goto quick_sample;
+               if (quickSampleCount++ < MAX_QUICK_SAMPLES)
+                       goto quick_sample;
        }
 
        // Slow sample
@@ -259,7 +270,8 @@
        deviation = conversionFactorSlower / conversionFactorSlow;
        if (deviation < 0.99 || deviation > 1.01) {
                // We might have been hit by a SMI or were otherwise stalled
-               goto slower_sample;
+               if (slowSampleCount++ < MAX_SLOW_SAMPLES)
+                       goto slower_sample;
        }
 
        // Scale the TSC delta to timer units
@@ -282,6 +294,22 @@
        gKernelArgs.arch_args.system_time_cv_factor = gTimeConversionFactor;
        gKernelArgs.arch_args.cpu_clock_speed = clockSpeed;
        //dprintf("factors: %lu %llu\n", gTimeConversionFactor, clockSpeed);
+
+       if (quickSampleCount > 1) {
+               dprintf("needed %lu quick samples for TSC calibration\n",
+                       quickSampleCount);
+       }
+
+       if (slowSampleCount > 1) {
+               dprintf("needed %lu slow samples for TSC calibration\n",
+                       slowSampleCount);
+       }
+
+       if (channel == 2) {
+               // Set the gate low again
+               out8(in8(PIT_CHANNEL_2_CONTROL) & ~PIT_CHANNEL_2_GATE_HIGH,
+                       PIT_CHANNEL_2_CONTROL);
+       }
 }
[haiku-commits] r41678 - haiku/trunk/src/system/boot/platform/bios_ia32

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