Kernelnewbies Digest, Vol 15, Issue 12

Kernelnewbies Digest, Vol 15, Issue 12

[Mayank Agarwal]

Hi all,

I want to contribute to camera dri*vers in linux kernel*.Please guide me
the procedure of doing that.

Regards,
Mayank

On Tue, Feb 7, 2012 at 10:30 PM, <kernelnewbies-request@kernelnewbies.org>wrote:

> Send Kernelnewbies mailing list submissions to
>        kernelnewbies at kernelnewbies.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
>        http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> or, via email, send a message with subject or body 'help' to
>        kernelnewbies-request at kernelnewbies.org
>
> You can reach the person managing the list at
>        kernelnewbies-owner at kernelnewbies.org
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Kernelnewbies digest..."
>
>
> Today's Topics:
>
>   1. Re: "Trying to free already-free IRQ 9", but it wasn't freed
>      by me (mayur nande)
>   2. Re: request_firmware question (Greg KH)
>   3. Re: fork() and exec() (Bernd Petrovitsch)
>   4. Re: make config errors while building kernel on Fedora 16
>      (Kartik Singhal)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 7 Feb 2012 20:33:31 +0530
> From: mayur nande <mayur.nan@gmail.com>
> Subject: Re: "Trying to free already-free IRQ 9", but it wasn't freed
>        by me
> To: "nils.stec" <nils.stec@googlemail.com>
> Cc: kernelnewbies <Kernelnewbies@kernelnewbies.org>
> Message-ID:
>        <CA+fM3Xy2QALrjbTYJxW0yKn-Q-Y99Wi8xUyyWtKEzYDTByTkjQ@mail.gmail.com
> >
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi Nils,
>
> >>void cleanup_module(void) {
>  >>   ...
>  >>  free_irq(ADC_IRQ, NULL);        /* remove interrupt handler */
>  >>  ...
>  >>   return;
> >>}
>
> You should not pass NULL here. It should be the unique cookie that you
> passed in request_irq (adc_irq_handler in your case) since you have used
> IRQF_SHARED which means you want to share your interrupt line. Also check
> whether you really want to share your interrupt line and also if you want
> to use "(void *)(adc_irq_handler)" as the unique identification.
>
> HTH!
>
> Regards
> Mayur
>
> On Tue, Feb 7, 2012 at 7:45 PM, nils.stec <nils.stec@googlemail.com>
> wrote:
>
> >  Hi,
> >
> > atm I'm writing a kernel module for an embedded ARM device.
> > This module uses IRQ9.
> >
> > If i remove the module, the kernel tells me that:
> >
> > ------------[ cut here ]------------
> > WARNING: at kernel/irq/manage.c:858 __free_irq+0x84/0x154()
> > Trying to free already-free IRQ 9
> > Modules linked in: adc_demo_irq(P-) g_ether pegasus mii
> > [<c0028794>] (unwind_backtrace+0x0/0xd0) from [<c003b504>]
> > (warn_slowpath_common+0x48/0x60)
> > [<c003b504>] (warn_slowpath_common+0x48/0x60) from [<c003b554>]
> > (warn_slowpath_fmt+0x24/0x30)
> > [<c003b554>] (warn_slowpath_fmt+0x24/0x30) from [<c005fa00>]
> > (__free_irq+0x84/0x154)
> > [<c005fa00>] (__free_irq+0x84/0x154) from [<c005fb0c>]
> > (free_irq+0x3c/0x5c)
> > [<c005fb0c>] (free_irq+0x3c/0x5c) from [<bf01e18c>]
> > (cleanup_module+0x4c/0x60 [adc_demo_irq])
> > [<bf01e18c>] (cleanup_module+0x4c/0x60 [adc_demo_irq]) from [<c005b898>]
> > (sys_delete_module+0x1c4/0x238)
> > [<c005b898>] (sys_delete_module+0x1c4/0x238) from [<c0022dc0>]
> > (ret_fast_syscall+0x0/0x28)
> > ---[ end trace 60d7a16d878ac0b3 ]---
> > adc testing module removed
> > ------------[ cut here ]------------
> >
> > The message "adc testing module removed" comes from my module
> **after**free_irq() via printk, so the module exit routine works till the
> end.
> >
> > This is my code (only the IRQ related part):
> >
> > irqreturn_t adc_irq_handler(int irq, void *dev_id) {
> >
> >     ... do someting ...
> >
> >     return IRQ_HANDLED;
> > }
> >
> > int init_module(void) {
> >     int32_t retval;
> >     ...
> >     retval = request_irq(ADC_IRQ, adc_irq_handler, IRQF_SHARED, "lpc313x
> > adc irq", (void *)(adc_irq_handler));
> >     ...
> >     return retval;
> > }
> >
> > void cleanup_module(void) {
> >     ...
> >     free_irq(ADC_IRQ, NULL);        /* remove interrupt handler */
> >     ...
> >     return;
> > }
> >
> >
> > I hope anyone of you can help me with that problem. If you need more
> > information, i'll send it
> >
> > Greetings,
> > Nils
> >
> > _______________________________________________
> > Kernelnewbies mailing list
> > Kernelnewbies at kernelnewbies.org
> > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> >
> >
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL:
> http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20120207/79cf9412/attachment-0001.html
>
> ------------------------------
>
> Message: 2
> Date: Tue, 7 Feb 2012 07:07:50 -0800
> From: Greg KH <greg@kroah.com>
> Subject: Re: request_firmware question
> To: anish kumar <anish198519851985@gmail.com>
> Cc: Kernelnewbies at kernelnewbies.org
> Message-ID: <20120207150750.GA7583@kroah.com>
> Content-Type: text/plain; charset=us-ascii
>
> On Tue, Feb 07, 2012 at 12:51:42AM -0800, anish kumar wrote:
> > Hi,
> >
> > Now I have switched to using request_firmware api
> > and after using firmware, memory is being released.
> > Does it save kernel memory compare to case when
> > I am having a having a local static firmware buffer(very big)
> > from which I used to get the firmware and write it
> > to the chip?
> >
> > As I know request_firmware api has several advantages
> > but what I want to know is the advantages related
> > to kernel memory footprint.
>
> Yes it is, as well as using the "proper" api for firmware loading, which
> means it fits into the rest of the kernel correctly.
>
> Also, no new drivers will be accepted that have static firmware blobs.
>
> greg k-h
>
>
>
> ------------------------------
>
> Message: 3
> Date: Tue, 07 Feb 2012 16:40:13 +0100
> From: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
> Subject: Re: fork() and exec()
> To: Vijay Chauhan <kernel.vijay@gmail.com>
> Cc: kernelnewbies at kernelnewbies.org
> Message-ID: <1328629213.25984.123.camel@thorin>
> Content-Type: text/plain; charset="UTF-8"
>
> On Die, 2012-02-07 at 00:38 +0530, Vijay Chauhan wrote:
> > Hi List,
> >
> > I am learning Linux and trying to understand exec and fork function.
> > execl says that it overlays the running address space. What does it mean?
> >
> > I created the following program and used top command with
> > intentionally wrong arguments:
> >
> > #include<stdio.h>
> > #include<unistd.h>
> > #include<sys/types.h>
> > #include<stdlib.h>
> >
> > int main(){
> >       int a = -1;
> >       if(fork()==0){
> >               printf("Inside child\n");
> >               printf("child pid=%d, parentid=%d\n", getpid(), getppid());
> >               execl("/usr/bin/top", "/usr/bin/top", ">/dev/null"
> ,(char*)0 );
>
> You get here only if the execl() as such fails.
>
> >               scanf("inside child provide a %d", &a);
>
> You should check the return value here if you actually got a matching
> parameter.
> scanf() is actually a function to be avoided.
>
> >               printf("Inside child a=%d\n", a);
> >               exit(1);
> >       } else {
> >               printf("Inside parent, going to wait\n");
> >               printf("my pid=%d, parentid=%d\n", getpid(), getppid());
> >               scanf("input parent %d\n", &a);
>
> You should check the return value here if you actually got a matching
> parameter.
> scanf() is actually a function to be avoided.
>
> >               wait(NULL);
>
> You should check the return value here to know why "wait()" returns.
>
> >               printf("Wait over\n");
> >               printf("Inside parent a=%d\n", a);
> >       }
> >       return 0;
> > }
>
>        Bernd
> --
> Bernd Petrovitsch                  Email : bernd at petrovitsch.priv.at
>                     LUGA : http://www.luga.at
>
>
>
>
> ------------------------------
>
> Message: 4
> Date: Tue, 7 Feb 2012 22:10:46 +0530
> From: Kartik Singhal <kartiksinghal@gmail.com>
> Subject: Re: make config errors while building kernel on Fedora 16
> To: Mulyadi Santosa <mulyadi.santosa@gmail.com>
> Cc: Kernelnewbies at kernelnewbies.org
> Message-ID:
>        <CAAY3Td5UJYmtqM5mzkBHug5bfMx0q5CoBd5CowtDNTdVrTORTQ@mail.gmail.com
> >
> Content-Type: text/plain; charset="utf-8"
>
> On Mon, Feb 6, 2012 at 1:05 PM, Mulyadi Santosa
> <mulyadi.santosa@gmail.com>wrote:
>
> > have you check their checksums?
>
>
> Is there a way to verify the checksums for git clones as in my case?
>
> --
> Kartik
> http://k4rtik.wordpress.com/
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL:
> http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20120207/3ff99cbf/attachment-0001.html
>
> ------------------------------
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>
>
> End of Kernelnewbies Digest, Vol 15, Issue 12
> *********************************************
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20120208/7cba4081/attachment-0001.html