lkml.org 
[lkml]   [2006]   [Dec]   [13]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [GIT PATCH] more Driver core patches for 2.6.19
FromThomas Gleixner <>
DateWed, 13 Dec 2006 23:30:55 +0100
On Thu, 2006-12-14 at 09:14 +1100, Benjamin Herrenschmidt wrote:
> the edge flow is easy. the level one is:> >  - IRQ happens
>  - kernel handler masks it and queue a msg for userland
>  - later on, userland gets the message, talks to the device,
>    (MMAP'ed mmio, acks the interrupt on the device itself) and
>    does an ioctl/syscall/write/whatever to tell kernel it's done
>  - kernel unmasks it.

That's simply not true.

- IRQ happens
- kernel handler runs and masks the chip irq, which removes the IRQ
request
- user space message get queued or waiting reader woken
- kernel handler returns IRQ_HANDLED, which reenables the irq in the PIC
- user space handles the device
- user space reenables the device irq

No need for an ioctl. Neither for edge nor for level irqs.

	tglx


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-12-13 23:29    [from the cache]
©2003-2008