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MIPS: Fix mdelay(1) for 64bit kernel with HZ == 1000
mdelay(1) (i.e. udelay(1000)) does not work correctly due to overflow. 1000 * 0x004189374BC6A7f0 = 0x10000000000000180 (>= 2**64) 0x004189374BC6A7ef (0x004189374BC6A7f0 - 1) is OK and it is exactly same as catchall case (0x8000000000000000UL / (500000 / HZ)). Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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1 changed files with 2 additions and 4 deletions
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@ -52,13 +52,11 @@ static inline void __udelay(unsigned long usecs, unsigned long lpj)
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unsigned long lo;
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/*
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* The common rates of 1000 and 128 are rounded wrongly by the
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* catchall case for 64-bit. Excessive precission? Probably ...
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* The rates of 128 is rounded wrongly by the catchall case
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* for 64-bit. Excessive precission? Probably ...
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*/
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#if defined(CONFIG_64BIT) && (HZ == 128)
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usecs *= 0x0008637bd05af6c7UL; /* 2**64 / (1000000 / HZ) */
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#elif defined(CONFIG_64BIT) && (HZ == 1000)
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usecs *= 0x004189374BC6A7f0UL; /* 2**64 / (1000000 / HZ) */
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#elif defined(CONFIG_64BIT)
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usecs *= (0x8000000000000000UL / (500000 / HZ));
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#else /* 32-bit junk follows here */
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