34 lines
968 B
Diff
34 lines
968 B
Diff
--- a/arch/mips/kernel/cevt-r4k.c
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+++ b/arch/mips/kernel/cevt-r4k.c
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@@ -23,6 +23,22 @@
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#ifndef CONFIG_MIPS_MT_SMTC
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+/*
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+ * Compare interrupt can be routed and latched outside the core,
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+ * so a single execution hazard barrier may not be enough to give
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+ * it time to clear as seen in the Cause register. 4 time the
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+ * pipeline depth seems reasonably conservative, and empirically
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+ * works better in configurations with high CPU/bus clock ratios.
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+ */
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+
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+#define compare_change_hazard() \
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+ do { \
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+ irq_disable_hazard(); \
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+ irq_disable_hazard(); \
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+ irq_disable_hazard(); \
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+ irq_disable_hazard(); \
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+ } while (0)
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+
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static int mips_next_event(unsigned long delta,
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struct clock_event_device *evt)
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{
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@@ -32,6 +48,7 @@ static int mips_next_event(unsigned long
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cnt = read_c0_count();
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cnt += delta;
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write_c0_compare(cnt);
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+ compare_change_hazard();
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res = ((int)(read_c0_count() - cnt) >= 0) ? -ETIME : 0;
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return res;
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}
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