nw i got the follwing result when i inserted this module:
----------------------------------------------------------------------
Oct 2 14:46:47 AnkurAggarwal kernel: Ank$: Hello module registered
successfully!
Oct 2 14:46:47 AnkurAggarwal kernel: Ank$: Memory allocation successful
Oct 2 14:46:47 AnkurAggarwal kernel: Ank$: Port Available
Oct 2 14:46:47 AnkurAggarwal kernel: Ank$:cdev successful
Oct 2 14:46:47 AnkurAggarwal kernel: Ank$: Generation of Interrupt starts
Oct 2 14:46:47 AnkurAggarwal kernel: Anks:ret:-16
Oct 2 14:46:47 AnkurAggarwal kernel: Press a key...
Oct 2 14:46:47 AnkurAggarwal kernel: >>> PARALLEL PORT INT HANDLED
Oct 2 14:46:47 AnkurAggarwal kernel: Ank$: ret=-16
Oct 2 14:46:47 AnkurAggarwal kernel: Generating interrupt now on all output
pins (intr/ACK = pin 10)
Oct 2 14:46:47 AnkurAggarwal kernel: Interrupt generated. You should see
the handler-message
-----------------------------------------------------------------------------------------------------------------------
the return value for request_irq() is negative but still it shows the
handler message. what could be the problem ???
i observed 1 thing in driver codes that enable_irq is rarely used after
request_irq(),but the tutorial i reffered used it. why so???
i will be glad for your inputs...
thanks
On Fri, Oct 2, 2009 at 1:39 PM, Jason Nymble <jason.nym...@gmail.com> wrote:
>
> On 02 Oct 2009, at 9:30 AM, Harinderjit Singh Sandhu wrote:
>
> i want to know which statement is turning it off.....
>
> On Thu, Oct 1, 2009 at 9:03 PM, Greg KH <g...@kroah.com> wrote:
>
>> On Thu, Oct 01, 2009 at 08:55:27PM +0530, Harinderjit Singh Sandhu wrote:
>> > this is the code for the small module that i wrote
>>
>> The problem is in your interrupt handler:
>>
>> > // interrupt handler
>> > irqreturn_t interrupt_handler (int irqn, void *dev)
>> > {
>> >
>> > printk("Press a key ");
>> >
>> >
>> > return IRQ_HANDLED;
>> >
>> >
>> > }
>>
>> You aren't really handling the interrupt by turning it off in the
>> hardware. So the kernel sees an interrupt storm for your device and
>> shuts it off to save the system from going crazy.
>>
>> What are you trying to do with this sample module?
>>
>> greg k-h
>>
>
> You need to clear the hardware interrupt in some way (to acknowledge to the
> hardware that you've seen it essentially). Often this means reading a
> register value. It depends on your hardware...
>
--
---------------------
Harinderjit Singh
Sent from Delhi, DL, India
--
---------------------
Harinderjit Singh
