El Thu, Mar 29, 2007 at 03:04:53PM +0530 Mansha Linux ha dit:
> On 3/29/07, Rajat Jain <[1]rajat.noida.india@xxxxxxxxx> wrote:
>
> On 3/29/07, Mansha Linux <[2]mansha.linux@xxxxxxxxx> wrote:
> >
> >
> > On 3/29/07, Rajat Jain <[3]rajat.noida.india@xxxxxxxxx> wrote:
> > > On 3/29/07, Mansha Linux < [4]mansha.linux@xxxxxxxxx> wrote:
> > > > hi all,
> > > >
> > > > When the external hardware device raise the interrupt the
> corresponding
> > ISR
> > > > will be executed.
> > > > but how this ISR will come to know about the source of interrupt.
> i mean
> > the
> > > > ISR will identify with respect to device id ..but when this device
> id is
> > > > passed to the ISR and as well as IRQ number?
> > >
> > > Hi Mansha,
> > >
> > > The ISR itself has the responsibility of detecting whether the
> device
> > > it serves, has raised the interrupt or not. Now how it confirms this
> > > from the device is quite device specific and may vary. But most of
> the
> > > devices have a status register kind of thing that you can test to
> see
> > > if it generated the interrupt.
> > >
> > > Also, getting the device ID of the device is also the resposibility
> of
> > > the ISR. But the most common approach is that when registering the
> > > ISR, you also pass the device ID to request_irq(). So the ISR will
> > > also get the device ID as parameter when it is called.
> > >
> > > Thanks,
> > >
> > > Rajat
> > >
> >
> >
> > Thanks for ur reply..
> >
> > >
> > > >
> > > > > The ISR itself has the responsibility of detecting whether the
> device
> > > > > it serves, has raised the interrupt or not. Now how it confirms
> this
> > > > > from the device is quite device specific and may vary. But most
> of the
> > > > > devices have a status register kind of thing that you can test
> to see
> > > > > if it generated the interrupt.
> > > > >
> > > >
> > > > Also, getting the device ID of the device is also the
> resposibility of
> > > > the ISR. But the most common approach is that when registering the
> > > > ISR, you also pass the device ID to request_irq(). So the ISR will
> > > > also get the device ID as parameter when it is called.
> > > >
> > >
> > >
> >
> >
> > -> ya, while registering the IRQ we will specify the divice id. but i
> wanted
> > to know how the ISR will confirms the device id because we are not
> passing
> > any divice id while interrupt is issued.
>
> Here is how it works:
>
> 1) The driver registers ISR for each device it services, also telling
> the kernel the corresponding device ID. This is done by calling
> request_irq().
>
> 2) When the IRQ occurs, the kernel invokes EACH and every ISR hooked
> onto that IRQ (Not just the ISR that actually services the device).
>
> 3) Each ISR receives its original device ID as parameter, it
> determines whether the corresponding device is the one that generated
> the IRQ.
>
> HTH,
>
> Rajat
>
> ok. but when the ISR receives the device id and who will pass this device
> id to the ISR ??
handle_IRQ_event() calls all ISRs of the IRQ passing the device id
with which the ISR was registered, and not necessarily the id of the
device that raised the interrupt
--
Matthias Kaehlcke
Linux Application Developer
Barcelona
If liberty means anything at all, it means the
right to tell people what they do not want to hear
(George Orwell)
.''`.
using free software / Debian GNU/Linux | http://debian.org : :' :
`. `'`
gpg --keyserver pgp.mit.edu --recv-keys 47D8E5D4 `-
--
To unsubscribe from this list: send an email with
"unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx
Please read the FAQ at http://kernelnewbies.org/FAQ
