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xtensa: fix __delay for small loop count 

Avoid __delay counter underflow for loop counts < 2.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
This commit is contained in:
Max Filippov 2013-10-17 02:42:16 +04:00 committed by Chris Zankel
parent 5515daa9ca
commit 01e3b3cb2d
1 changed files with 6 additions and 3 deletions
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9
arch/xtensa/include/asm/delay.h
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@ -19,9 +19,12 @@ extern unsigned long loops_per_jiffy;
static inline void __delay(unsigned long loops)
{
/* 2 cycles per loop. */
__asm__ __volatile__ ("1: addi %0, %0, -2; bgeui %0, 2, 1b"
: "=r" (loops) : "0" (loops));
if (__builtin_constant_p(loops) && loops < 2)
__asm__ __volatile__ ("nop");
else if (loops >= 2)
/* 2 cycles per loop. */
__asm__ __volatile__ ("1: addi %0, %0, -2; bgeui %0, 2, 1b"
: "+r" (loops));
}
/* For SMP/NUMA systems, change boot_cpu_data to something like