Gaurav Dhiman wrote:
On 5/10/06, Christian Boon <c.boon@xxxxxxxxxxxxxxxxxxxx> wrote:
Gaurav Dhiman wrote:
> On 5/10/06, Christian Boon <c.boon@xxxxxxxxxxxxxxxxxxxx> wrote:
>
>> Hello,
>>
>> i've got a question.
>> i have a module with an interrupt line connected to a fifo
>
>
> what does this mean, please explain more.
It means when receiving an interrupt a fifo is filled with data and it
takes some time until the fifo is full.
when i start reading the fifo right away, i would read the fifo faster
then the fifo is filled so there has to
be a delay of around 400 uS..
See processes waiting on your FIFO will be sleeping as you FIFO is
emply, now when interrupt occurs and fills up the FIFO, once the FIFO
is filled up, it should wake up the sleeping processes on that FIFO
and once those will be waked up only then the process will try to read
the FIFO, so there is no problem of readin the FIFO afst than filling
it up.
when the FIFO is empty put the process on sleep on some waiting queue
and once the interrupt handlers fills the FIFO then only wake up the
sleeping processes from interrupt context.
In case I did not understand your problem fully, correct me.
Thanks for your help,
The signal that causes the interrupt is also connected to the write
enable (start filling fifo) of the fifo, so that means
when an interrupt occurs, the fifo is being triggered to fill itself
with data from an ADC.
There is no signal to wake up the process on the wait queue because only
the interrupt
causes the fifo to be filled, there is no signal that says: the fifo is
full now.
So what i want is:
interrupt -> wait for 400 uS --> read fifo --> send fifo data to userspace.
the only problem i have is the delay, the rest is obvious to me.
Christian.
>
>> is it possible to wait after an interrupt for 400 uS before
execution a
>> function (reading the fifo)?
>
>
> why you want to wait in interrupt handler, not a good idea atall.
I dont want to wait in an interrupt handler, i just want to delay
reading the fifo because otherwise the fifo won't be filled yet.
I know there are bottom halves to delay execution of a specific
function, but those are always in the range of jiffies, not micro
seconds.
Christian.
--
Gaurav
Email: gauravd.chd@xxxxxxxxx
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