Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753090AbaFMQGO (ORCPT ); Fri, 13 Jun 2014 12:06:14 -0400 Received: from mail-vc0-f174.google.com ([209.85.220.174]:41576 "EHLO mail-vc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750901AbaFMQGN (ORCPT ); Fri, 13 Jun 2014 12:06:13 -0400 MIME-Version: 1.0 In-Reply-To: <1402603992-12466-2-git-send-email-davidriley@chromium.org> References: <1402603992-12466-1-git-send-email-davidriley@chromium.org> <1402603992-12466-2-git-send-email-davidriley@chromium.org> Date: Fri, 13 Jun 2014 09:06:12 -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 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. 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/