[PATCH 1/2] Xext: Fix edge case with {Positive, Negative}Transition triggers.
Christopher James Halse Rogers
christopher.halse.rogers at canonical.com
Mon Aug 23 20:48:03 PDT 2010
The {Positive,Negative}Transition triggers only fire when the counter
goes from strictly {below,above} the threshold. If
SyncComputeBracketValues gets called exactly at this threshold we may update
the bracket values so that the counter is not updated past the threshold.
Signed-off-by: Christopher James Halse Rogers <christopher.halse.rogers at canonical.com>
---
Xext/sync.c | 22 ++++++++++++++++++++++
1 files changed, 22 insertions(+), 0 deletions(-)
diff --git a/Xext/sync.c b/Xext/sync.c
index a51262a..c00e692 100644
--- a/Xext/sync.c
+++ b/Xext/sync.c
@@ -959,6 +959,17 @@ SyncComputeBracketValues(SyncCounter *pCounter)
{
psci->bracket_less = pTrigger->test_value;
pnewltval = &psci->bracket_less;
+ } else if (XSyncValueEqual(pCounter->value, pTrigger->test_value) &&
+ XSyncValueLessThan(pTrigger->test_value,
+ psci->bracket_greater))
+ {
+ /*
+ * The value is exactly equal to our threshold. We want one
+ * more event in the positive direction to ensure we pick up
+ * when the value *exceeds* this threshold.
+ */
+ psci->bracket_greater = pTrigger->test_value;
+ pnewgtval = &psci->bracket_greater;
}
}
else if (pTrigger->test_type == XSyncPositiveTransition &&
@@ -969,6 +980,17 @@ SyncComputeBracketValues(SyncCounter *pCounter)
{
psci->bracket_greater = pTrigger->test_value;
pnewgtval = &psci->bracket_greater;
+ } else if (XSyncValueEqual(pCounter->value, pTrigger->test_value) &&
+ XSyncValueGreaterThan(pTrigger->test_value,
+ psci->bracket_less))
+ {
+ /*
+ * The value is exactly equal to our threshold. We want one
+ * more event in the negative direction to ensure we pick up
+ * when the value is less than this threshold.
+ */
+ psci->bracket_less = pTrigger->test_value;
+ pnewltval = &psci->bracket_less;
}
}
} /* end for each trigger */
--
1.7.1
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