[PATCH] powerpc: Fix shared processor and mdelay interaction
From: Anton Blanchard <hidden>
Date: 2006-06-10 11:25:21
Paul and Ben found an interaction with mdelay on shared processor where mdelay can have large errors. Signed-off-by: Anton Blanchard <redacted> --- Index: build/include/asm-powerpc/delay.h ===================================================================
--- build.orig/include/asm-powerpc/delay.h 2006-06-08 10:57:41.000000000 +1000
+++ build/include/asm-powerpc/delay.h 2006-06-10 21:15:02.000000000 +1000@@ -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 */
Index: build/include/linux/delay.h ===================================================================
--- build.orig/include/linux/delay.h 2006-06-08 10:57:41.000000000 +1000
+++ build/include/linux/delay.h 2006-06-10 21:04:58.000000000 +1000@@ -25,10 +25,7 @@ extern unsigned long loops_per_jiffy; #define MAX_UDELAY_MS 5 #endif -#ifdef notdef -#define mdelay(n) (\ - {unsigned long __ms=(n); while (__ms--) udelay(1000);}) -#else +#ifndef mdelay #define mdelay(n) (\ (__builtin_constant_p(n) && (n)<=MAX_UDELAY_MS) ? udelay((n)*1000) : \ ({unsigned long __ms=(n); while (__ms--) udelay(1000);}))