Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753583AbaFMQWW (ORCPT ); Fri, 13 Jun 2014 12:22:22 -0400 Received: from mail-vc0-f182.google.com ([209.85.220.182]:33475 "EHLO mail-vc0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753176AbaFMQWV (ORCPT ); Fri, 13 Jun 2014 12:22:21 -0400 MIME-Version: 1.0 In-Reply-To: References: <1402603992-12466-1-git-send-email-davidriley@chromium.org> <1402603992-12466-2-git-send-email-davidriley@chromium.org> Date: Fri, 13 Jun 2014 09:22:21 -0700 Message-ID: Subject: Re: [PATCH v3 1/2] kernel: time: Add udelay_test module to validate udelay From: John Stultz To: David Riley Cc: Thomas Gleixner , Doug Anderson , lkml Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 13, 2014 at 9:13 AM, David Riley wrote: > On Fri, Jun 13, 2014 at 9:06 AM, John Stultz wrote: >> On Thu, Jun 12, 2014 at 1:13 PM, David Riley wrote: >>> Create a module that allows udelay() to be executed to ensure that >>> it is delaying at least as long as requested (with a little bit of >>> error allowed). >>> >>> There are some configurations which don't have reliably udelay >>> due to using a loop delay with cpufreq changes which should use >>> a counter time based delay instead. This test aims to identify >>> those configurations where timing is unreliable. >>> >>> Signed-off-by: David Riley >>> --- >>> kernel/time/Kconfig | 7 ++ >>> kernel/time/Makefile | 1 + >>> kernel/time/udelay_test.c | 170 ++++++++++++++++++++++++++++++++++++++++++++++ >>> 3 files changed, 178 insertions(+) >>> create mode 100644 kernel/time/udelay_test.c >>> >>> diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig >>> index f448513..c6af048 100644 >>> --- a/kernel/time/Kconfig >>> +++ b/kernel/time/Kconfig >>> @@ -202,3 +202,10 @@ config HIGH_RES_TIMERS >>> >>> endmenu >>> endif >>> + >>> +config UDELAY_TEST >>> + tristate "udelay test driver" >>> + default n >>> + help >>> + This builds the "udelay_test" module that helps to make sure >>> + that udelay() is working properly. >> >> >> Thanks for resubmitting! So I've queued this for my testing. >> >> My only thoughts playing with it now, is that the Kconfig entry is >> just in an awkward spot. There isn't really a udelay, or really >> general timekeeping specific area in the menus, so it just shows up in >> "General Setup" between the "Timer Subsystem" and "Cpu/task time.." >> submenus. >> >> I suspect this would be better added in lib/Kconfig.debug near >> TEST_MODULE. Any objections to me changing that? >> >> Also I'd probably rename the config option to TEST_UDELAY, as well as >> tweak the option string to be more consistent with those similar test >> driver options. > > Hi John, > > I'm okay with those changes. Do you want me to resubmit or will you > just make the changes locally? Don't bother, already made them locally.. thanks -john -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/