On Wed, Apr 7, 2010 at 15:19, Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net> wrote:

On 03.04.2010 23:09, Carl-Daniel Hailfinger wrote:

> On 03.04.2010 01:28, Urja Rannikko wrote:
>
>> This seems to "fix" this for me - the delay loop is still unreliable, but
>> atleast the recalibration attempts only take 5s instead of minutes. This is
>> a combined diff for both my fix and the % fix.
>>
>> Index: udelay.c
>> ===================================================================
>> --- udelay.c (revision 990)
>> +++ udelay.c (working copy)
>> @@ -66,6 +66,7 @@
>>      printf("Calibrating delay loop... ");
>>
>>  recalibrate:
>> +    count = 1000;
>>      while (1) {
>>              timeusec = measure_delay(count);
>>              if (timeusec > 1000000 / 4)
>>
>>
>
> Does the timing get more reliable if you try the following stuff:
>
> - change the comparison above to
>
> if (timeusec > 1000)
>

I expect this little change to improve precision dramatically.

> - Make sure there are no CPU frequency changes or sleep states
>
>

>> Signed-off-by: Urja Rannikko <urjaman@gmail.com>
>>
>
> In general, I like your patch. I just hope to get more input if reducing
> the abort condition in the loop from 250 ms to 1 ms helps as well.
>

We need your patch, I had just hoped that improved precision would be
possible with the additional change I suggested. Anyway, this is
Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>

Can you commit?

If I would have commit access ;)

I'm sorry that i forgot about this until now (real life+work had priority) - I just changed my mb from the failing (in many ways) Asus K8S-MX to a M4N78-AM.

For this MB the delay loop is accurate with if (timeusec > 1000000 / 4).
Just for reference - M4N78-AM:
"timeusec < 1000" - 3 runs:
Calibrating delay loop... 1156M loops per second, 10 myus = 10 us, 100 myus = 101 us, 1000 myus = 1148 us, 10000 myus = 10998 us, OK.
Calibrating delay loop... 1156M loops per second, 10 myus = 10 us, 100 myus = 101 us, 1000 myus = 1092 us, 10000 myus = 13070 us, OK.
Calibrating delay loop... 1146M loops per second, 10 myus = 10 us, 100 myus = 181 us, 1000 myus = 996 us, 10000 myus = 10807 us, OK.

"timeusec > 1000000 / 4" - 3 runs:
Calibrating delay loop... 1153M loops per second, 10 myus = 10 us, 100 myus = 100 us, 1000 myus = 998 us, 10000 myus = 10003 us, OK.
Calibrating delay loop... 1154M loops per second, 10 myus = 10 us, 100 myus = 100 us, 1000 myus = 1004 us, 10000 myus = 10014 us, OK.
Calibrating delay loop... 1132M loops per second, 10 myus = 10 us, 100 myus = 98 us, 1000 myus = 987 us, 10000 myus = 10442 us, OK.

I dont (atleast Right Now - i dont know what I will do with that K8S-MX) want to take my new shiny system apart just to put that MB from '05 back for running flashrom a few times on it, sorry.