[PATCH RESEND] ixp4xx: clockevent set_next_event fix (TESTERS NEEDED)

[michal.wrobel@flytronic.pl (Michał Wróbel)]

On 14.02.2012 13:21, Micha? Wr?bel wrote:
> On 14.02.2012 13:01, Richard Cochran wrote:
>> On Tue, Feb 14, 2012 at 10:55:05AM +0100, Micha? Wr?bel wrote:
>>> IXP43x Developer's Manual [17.4.3] and IXP4[56]x Developer's Manual
>>> [18.4.3] say that (...)
>>>
>>> IXP42x Developer's Manual [14.3] says that (...)
>> Unless you test this out and confirm that it works for all IXP4xx, I
>> would prefer to see a specific timer function for the 43x instead.
>>
>> Thanks,
>> Richard
> I think I might have some IXP425-based boards available for testing.
I will have it available later.
> However, I certainly don't have any IXP45x- or IXP46x-based board.
> Maybe I'll prepare a small kernel module that will allow to easily test this
> issue
Done. See the attachments.

Results of my tests performed on IXP435-based board (667 MHz,
CONFIG_HZ=100) follow below.

Without the patch:

starting measurements: 10000 samples * 1000000 ns
measurements finished
min: 2500 ns
avg: 7894228 ns
max: 9970743 ns

With the patch:

starting measurements: 10000 samples * 1000000 ns
measurements finished
min: 1637 ns
avg: 4266 ns
max: 100182 ns

>  by other list members who have IXP45x- and IXP46x-based boards?
Does anyone have any IXP45x- and IXP46x-based board? If so, I would like
to ask to compile ixp4xx_set_next_event_bug_test.c as a module and run
it on such a board. Then, to apply the "ixp4xx: clockevent
set_next_event fix" patch and re-run the tests. Of course, finally
posting the results here.

Note that the kernel used for testing has to be configured with
CONFIG_HIGH_RES_TIMERS=y

Thank you in advance!

Best regards,
Micha?

>>> Signed-off-by: Micha? Wr?bel <michal.wrobel@flytronic.pl>
>>> ---
>>>  arch/arm/mach-ixp4xx/common.c |    1 +
>>>  1 files changed, 1 insertions(+), 0 deletions(-)
>>> (...)
>>> diff --git a/arch/arm/mach-ixp4xx/common.c b/arch/arm/mach-ixp4xx/common.c
>>> index 3841ab4..fd37c83 100644
>>> --- a/arch/arm/mach-ixp4xx/common.c
>>> +++ b/arch/arm/mach-ixp4xx/common.c
>>> @@ -434,6 +434,7 @@ static int ixp4xx_set_next_event(unsigned long evt,
>>>  {
>>>  	unsigned long opts = *IXP4XX_OSRT1 & IXP4XX_OST_RELOAD_MASK;
>>>  
>>> +	*IXP4XX_OSRT1 = 0;
>>>  	*IXP4XX_OSRT1 = (evt & ~IXP4XX_OST_RELOAD_MASK) | opts;
>>>  
>>>  	return 0;
>>> -- 
>>> 1.7.5.4


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