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-rw-r--r--include/asm-powerpc/delay.h13
1 files changed, 13 insertions, 0 deletions
diff --git a/include/asm-powerpc/delay.h b/include/asm-powerpc/delay.h
index 057a60955474..f9200a65c632 100644
--- a/include/asm-powerpc/delay.h
+++ b/include/asm-powerpc/delay.h
@@ -17,5 +17,18 @@
extern void __delay(unsigned long loops);
extern void udelay(unsigned long usecs);
+/*
+ * On shared processor machines the generic implementation of mdelay can
+ * result in large errors. While each iteration of the loop inside mdelay
+ * is supposed to take 1ms, the hypervisor could sleep our partition for
+ * longer (eg 10ms). With the right timing these errors can add up.
+ *
+ * Since there is no 32bit overflow issue on 64bit kernels, just call
+ * udelay directly.
+ */
+#ifdef CONFIG_PPC64
+#define mdelay(n) udelay((n) * 1000)
+#endif
+
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_DELAY_H */
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