From 01e3b3cb2d70ca9d95769e863ca71a85f84c3917 Mon Sep 17 00:00:00 2001 From: Max Filippov Date: Thu, 17 Oct 2013 02:42:16 +0400 Subject: [PATCH] xtensa: fix __delay for small loop count Avoid __delay counter underflow for loop counts < 2. Signed-off-by: Max Filippov Signed-off-by: Chris Zankel --- arch/xtensa/include/asm/delay.h | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/xtensa/include/asm/delay.h b/arch/xtensa/include/asm/delay.h index 3899610c1dff..742b89f3ca2c 100644 --- a/arch/xtensa/include/asm/delay.h +++ b/arch/xtensa/include/asm/delay.h @@ -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 -- 2.20.1