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>
diff --git a/arch/xtensa/include/asm/delay.h b/arch/xtensa/include/asm/delay.h
index 3899610c..742b89f 100644
--- a/arch/xtensa/include/asm/delay.h
+++ b/arch/xtensa/include/asm/delay.h
@@ -19,9 +19,12 @@
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