From: Max Filippov <jcmvbkbc@gmail.com>
To: Chris Zankel <chris@zankel.net>
Cc: Marc Gauthier <marc@tensilica.com>,
linux-xtensa@linux-xtensa.org, linux-arch@vger.kernel.org,
Max Filippov <jcmvbkbc@gmail.com>
Subject: [PATCH 05/17] xtensa: fix __delay for small loop count
Date: Thu, 17 Oct 2013 02:42:16 +0400 [thread overview]
Message-ID: <1381963348-29448-6-git-send-email-jcmvbkbc@gmail.com> (raw)
In-Reply-To: <1381963348-29448-1-git-send-email-jcmvbkbc@gmail.com>
Avoid __delay counter underflow for loop counts < 2.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
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 3899610..742b89f 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
--
1.8.1.4
next prev parent reply other threads:[~2013-10-16 22:42 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-16 22:42 [PATCH 00/17] xtensa SMP queue Max Filippov
2013-10-16 22:42 ` [PATCH 01/17] xtensa: remove NO_IRQ definitions Max Filippov
2013-10-16 22:42 ` [PATCH 02/17] xtensa: fix build warning in 64-bit build environment Max Filippov
2013-10-16 22:42 ` [PATCH 03/17] xtensa: fix build warning from gcc-4.7.2 Max Filippov
2013-10-16 22:42 ` [PATCH 04/17] xtensa: fix arch spinlock function names Max Filippov
2013-10-16 22:42 ` Max Filippov [this message]
2013-10-16 22:42 ` [PATCH 06/17] xtensa: enable HAVE_IRQ_TIME_ACCOUNTING Max Filippov
2013-10-16 22:42 ` [PATCH 07/17] xtensa: mark ccount as continuous clocksource Max Filippov
2013-10-16 22:42 ` [PATCH 08/17] xtensa: update clockevent setup for SMP Max Filippov
2013-10-16 22:42 ` [PATCH 09/17] xtensa: call check_s32c1i after trap_init Max Filippov
2013-10-16 22:42 ` [PATCH 10/17] xtensa: move init_mmu declaration to mmu_context.h Max Filippov
2013-10-16 22:42 ` [PATCH 11/17] xtensa: move built-in PIC to drivers/irqchip Max Filippov
2013-10-16 22:42 ` [PATCH 12/17] xtensa: clean up do_interrupt/do_IRQ Max Filippov
2013-10-16 22:42 ` [PATCH 13/17] xtensa: clear timer IRQ unconditionally in its handler Max Filippov
2013-10-16 22:42 ` [PATCH 14/17] xtensa: add MX irqchip Max Filippov
2013-10-16 22:42 ` [PATCH 15/17] xtensa: add SMP support Max Filippov
2013-10-16 22:42 ` [PATCH 16/17] xtensa: add Three Core HiFi-2 MX Variant Max Filippov
2013-10-16 22:42 ` [PATCH 17/17] xtensa: implement CPU hotplug Max Filippov
2013-11-19 4:05 ` [PATCH 00/17] xtensa SMP queue Chris Zankel
2013-11-19 6:36 ` Max Filippov
2013-11-19 6:45 ` czankel
2013-12-01 5:38 ` [PATCHv2 14/17] xtensa: add MX irqchip Max Filippov
2013-12-01 7:20 ` [Linux-Xtensa] " Baruch Siach
2013-12-01 8:07 ` Max Filippov
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