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SubjectRe: [PATCH v3 1/2] kernel: time: Add udelay_test module to validate udelay
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On Fri, Jun 13, 2014 at 9:13 AM, David Riley <davidriley@google.com> wrote:
> On Fri, Jun 13, 2014 at 9:06 AM, John Stultz <john.stultz@linaro.org> wrote:
>> On Thu, Jun 12, 2014 at 1:13 PM, David Riley <davidriley@chromium.org> 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 <davidriley@chromium.org>
>>> ---
>>> 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


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