[Newbie] Interrupt Handling and sleep/wake_up

[Newbie] Interrupt Handling and sleep/wake_up

[Christian Vogel]

Hi,

-- Warning, newbie qeustion! --

currently I'm trying to write a very simple driver for the NI-GPIB-PCII
card and I'm mostly copying what was linux-gpib a long time ago.

Why am I writing to this list? I think I miss some obvious solution to a
problem. The problem lies within my handling of interrupts, let my try a
simplified example:

The board signals arrival of new data, it's ability to accept new data
or errors via the interrupt. I want my program to sleep until enough
data has been accepted or an error has occured.

Unfortunately on errors the interrupt hits just before I call
sleep_on_timeout() and because it's the only interrupt in this case
that's being generated I have to wait until sleep_on_timeout()
timeout's.

The old driver mostly uses
	while(!condition && !i++>threshold)
		udelay()
which I would like to avoid.

What would be the preferred way of doing this and what am I missing?

Some simple pseudocode follows to illustrate my point: bdIrq
is the interrupt-service-routine, bdDoSomething is called via
device->file-operations->read/write->... and wants to fetch something
from the card or write to it.

void bdIrq(int irq,void *data, struct pt_regs *regs){
	query_board_for_status();
	if( board_has_data_available )
		readbuf[readcounter++]=inb(data_port);
	if( board_can_accept_data )
		outb(wrbuf[writecounter++],data_port);
	if( board_has_error_condition_set )
		board_has_error = 1;
	if( buffer_full_or_end_of_data || board_has_error )
		wake_up_interruptible(&irq_wqueue);
}

void bdDoSomething(){
	setup_buffers_for_interrupt_routing();
	tell_board_to_start_reading_or_writing();
	/***** BOARD THROWS ITS INTERRUPTS HERE!!! *****/
	interruptible_sleep_on_timeout(&irq_wqueue,PCIIA_SLEEP_TIMEOUT);
}

	Chris

-- 
Is it true that cannibals won't eat clowns because they taste funny?

[Newbie] Interrupt Handling and sleep/wake_up

[Manfred Spraul]

> void bdDoSomething(){
>         setup_buffers_for_interrupt_routing();
>         tell_board_to_start_reading_or_writing();
>         /***** BOARD THROWS ITS INTERRUPTS HERE!!! *****/
>         interruptible_sleep_on_timeout(&irq_wqueue,PCIIA_SLEEP_TIMEOUT);
> }
> 
Just do not use sleep_on, use wait_event or a manual wait loop.

check the mouse driver sample from Alan Cox:
	linux/Documentation/DocBook/mousedriver.tmpl

The document is slightly outdated:

* do not access current->state directly, use set_current_state.
* do not use MOD_INC_USE_COUNT, set module->owner to THIS_MODULE
instead.

--
	Manfred

Re: [Newbie] Interrupt Handling and sleep/wake_up

[Alan Cox]

> check the mouse driver sample from Alan Cox:
> 	linux/Documentation/DocBook/mousedriver.tmpl
> 
> The document is slightly outdated:
> 
> * do not access current->state directly, use set_current_state.
> * do not use MOD_INC_USE_COUNT, set module->owner to THIS_MODULE
> instead.

Thanks: Updated