From: Vijay Nikam <vijay.t.nikam@gmail.com>
To: michael@ellerman.id.au
Cc: linuxppc-dev@ozlabs.org
Subject: Re: request_irq return errno 38
Date: Wed, 11 Feb 2009 15:43:26 +0530 [thread overview]
Message-ID: <f234e2140902110213g3ae48f2es9fe41087bc8c7b39@mail.gmail.com> (raw)
In-Reply-To: <1234346072.9778.20.camel@localhost>
Ok ... so that means if I am writing driver for any device I need to
take care of this mapping ? ? ? I mean I should use virq ? ? ?
I read in LDD book, they give directly irq no. they have given
parallel port example, here they have set or said irq no. defaults to
7 and they have not done any irq_mapping so what is the difference ? ?
? I mean how I should know when to use irq_mapping and when not ? ? ?
Also is it some difference between writng drivers on embedded Linux
level and Linux PC (i386) ? ? ?
Sorry for perhaps these basic questions as kind of new to Linux kernel
programming ... :-)
Kindly please acknowledge ... thank you ...
Kind Regards,
Vijay Nikam
On 2/11/09, Michael Ellerman <michael@ellerman.id.au> wrote:
> On Wed, 2009-02-11 at 15:11 +0530, Vijay Nikam wrote:
> > Thanks for your prompt reply ...
> >
> > I am using kernel version 2.6.20 ...
>
> OK, that kernel has the irq remapping stuff.
>
> > May I know what raw IRQ means ? ? ? and what is the reason I cant map
> > raw_irq_number ???
>
> Sorry, that's not the best terminology.
>
> I guess the right name is hardware irq number.
>
> You can't map it because the kernel keeps a mapping between hardware irq
> numbers and virtual irq numbers. request_irq() expects a virtual irq
> number.
>
> cheers
>
> --
> Michael Ellerman
> OzLabs, IBM Australia Development Lab
>
> wwweb: http://michael.ellerman.id.au
> phone: +61 2 6212 1183 (tie line 70 21183)
>
> We do not inherit the earth from our ancestors,
> we borrow it from our children. - S.M.A.R.T Person
>
>
next prev parent reply other threads:[~2009-02-11 10:13 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-11 8:43 request_irq return errno 38 Vijay Nikam
2009-02-11 9:15 ` Michael Ellerman
2009-02-11 9:41 ` Vijay Nikam
2009-02-11 9:54 ` Michael Ellerman
2009-02-11 10:13 ` Vijay Nikam [this message]
2009-02-11 22:35 ` Brad Boyer
2009-02-12 6:01 ` Benjamin Herrenschmidt
2009-02-12 10:51 ` Vijay Nikam
2009-02-12 16:39 ` Timur Tabi
2009-02-12 22:49 ` David Gibson
2009-02-11 22:48 ` Scott Wood
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