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Commit f12555d2 authored by Atsushi Nemoto's avatar Atsushi Nemoto Committed by
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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: default avatarAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 6c355852

include/asm-mips/delay.h

+2 −4
Original line number Diff line number Diff line
@@ -52,13 +52,11 @@ static inline void __udelay(unsigned long usecs, unsigned long lpj) 
	unsigned long lo;



	/*

	 * The common rates of 1000 and 128 are rounded wrongly by the

	 * catchall case for 64-bit.  Excessive precission?  Probably ...

	 * The rates of 128 is rounded wrongly by the catchall case

	 * for 64-bit.  Excessive precission?  Probably ...

	 */

#if defined(CONFIG_64BIT) && (HZ == 128)

	usecs *= 0x0008637bd05af6c7UL;		/* 2**64 / (1000000 / HZ) */

#elif defined(CONFIG_64BIT) && (HZ == 1000)

	usecs *= 0x004189374BC6A7f0UL;		/* 2**64 / (1000000 / HZ) */

#elif defined(CONFIG_64BIT)

	usecs *= (0x8000000000000000UL / (500000 / HZ));

#else /* 32-bit junk follows here */