Question: 20 microseconds delay

Question: 20 microseconds delay

[Mockern]

Hi,

I have a question.

I need to use 20 microsecond delay in my driver.
What exact jiffies value I should define to get 20 microseconds?

Thank you

Re: Question: 20 microseconds delay

[Jiri Slaby]

Mockern napsal(a):
> Hi,
> 
> I have a question.
> 
> I need to use 20 microsecond delay in my driver.
> What exact jiffies value I should define to get 20 microseconds?

It's subjiffy delay unless you use 50000 HZ :). Use udelay.

regards,
-- 
http://www.fi.muni.cz/~xslaby/            Jiri Slaby
faculty of informatics, masaryk university, brno, cz
e-mail: jirislaby gmail com, gpg pubkey fingerprint:
B674 9967 0407 CE62 ACC8  22A0 32CC 55C3 39D4 7A7E

Hnus <hnus@fi.muni.cz> is an alias for /dev/null

Re: Question: 20 microseconds delay

[Hans-Jürgen Koch]

Am Samstag 03 März 2007 15:20 schrieb Mockern:
> Hi,
>
> I have a question.
>
> I need to use 20 microsecond delay in my driver.
> What exact jiffies value I should define to get 20 microseconds?

You can't do it with jiffies as they have 1 millisecond resolution at best. 
You'd use something like usleep(20) instead.

Hans

Re: Question: 20 microseconds delay

[Mockern]

The problem is that I need to use wait_event_timeout function.

>Mockern napsal(a):
>> Hi,
>> 
>> I have a question.
>> 
>> I need to use 20 microsecond delay in my driver.
>> What exact jiffies value I should define to get 20 microseconds?
>
>It's subjiffy delay unless you use 50000 HZ :). Use udelay.
>
>regards,

-- 
Яндекс.Почта: объем почтового ящика не ограничен! http://mail.yandex.ru/monitoring/

Re: Question: 20 microseconds delay

[Mockern]

The problem is that I need to use wait_event_timeout function 

>Am Samstag 03 Mдrz 2007 15:20 schrieb Mockern:
>> Hi,
>>
>> I have a question.
>>
>> I need to use 20 microsecond delay in my driver.
>> What exact jiffies value I should define to get 20 microseconds?
>
>You can't do it with jiffies as they have 1 millisecond resolution at best. 
>You'd use something like usleep(20) instead.
>
>Hans
>
>-
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Re: Question: 20 microseconds delay

[Jiri Slaby]

Do not top-post, please.

Mockern napsal(a):
>> Mockern napsal(a):
>>> I need to use 20 microsecond delay in my driver.
>>> What exact jiffies value I should define to get 20 microseconds?
>> It's subjiffy delay unless you use 50000 HZ :). Use udelay.
 >
> The problem is that I need to use wait_event_timeout function.

Hardly. Place a piece of code here or describe what do you want to achieve.

regards,
-- 
http://www.fi.muni.cz/~xslaby/            Jiri Slaby
faculty of informatics, masaryk university, brno, cz
e-mail: jirislaby gmail com, gpg pubkey fingerprint:
B674 9967 0407 CE62 ACC8  22A0 32CC 55C3 39D4 7A7E

Hnus <hnus@fi.muni.cz> is an alias for /dev/null

Re: Question: 20 microseconds delay

[Bill Davidsen]

Mockern wrote:
> The problem is that I need to use wait_event_timeout function 

AFAIK you can't do that, it's just not the right tool for the job. You 
can always use a single jiffy and be sure you will wait at least 20us, 
or use usleep.

No matter how much you "need to use" your snowblower, it won't mow your 
lawn.

-- 
Bill Davidsen <davidsen@tmr.com>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot