Hi all,<br><br>I want to contribute to camera dri<u>vers in linux kernel</u>.Please guide me the procedure of doing that.<br><br>Regards,<br>Mayank<br><br><div class="gmail_quote">On Tue, Feb 7, 2012 at 10:30 PM, <span dir="ltr"><<a href="mailto:kernelnewbies-request@kernelnewbies.org">kernelnewbies-request@kernelnewbies.org</a>></span> wrote:<br>
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Today's Topics:<br>
<br>
1. Re: "Trying to free already-free IRQ 9", but it wasn't freed<br>
by me (mayur nande)<br>
2. Re: request_firmware question (Greg KH)<br>
3. Re: fork() and exec() (Bernd Petrovitsch)<br>
4. Re: make config errors while building kernel on Fedora 16<br>
(Kartik Singhal)<br>
<br>
<br>
----------------------------------------------------------------------<br>
<br>
Message: 1<br>
Date: Tue, 7 Feb 2012 20:33:31 +0530<br>
From: mayur nande <<a href="mailto:mayur.nan@gmail.com">mayur.nan@gmail.com</a>><br>
Subject: Re: "Trying to free already-free IRQ 9", but it wasn't freed<br>
by me<br>
To: "nils.stec" <<a href="mailto:nils.stec@googlemail.com">nils.stec@googlemail.com</a>><br>
Cc: kernelnewbies <<a href="mailto:Kernelnewbies@kernelnewbies.org">Kernelnewbies@kernelnewbies.org</a>><br>
Message-ID:<br>
<<a href="mailto:CA%2BfM3Xy2QALrjbTYJxW0yKn-Q-Y99Wi8xUyyWtKEzYDTByTkjQ@mail.gmail.com">CA+fM3Xy2QALrjbTYJxW0yKn-Q-Y99Wi8xUyyWtKEzYDTByTkjQ@mail.gmail.com</a>><br>
Content-Type: text/plain; charset="iso-8859-1"<br>
<br>
Hi Nils,<br>
<br>
>>void cleanup_module(void) {<br>
>> ...<br>
>> free_irq(ADC_IRQ, NULL); /* remove interrupt handler */<br>
>> ...<br>
>> return;<br>
>>}<br>
<br>
You should not pass NULL here. It should be the unique cookie that you<br>
passed in request_irq (adc_irq_handler in your case) since you have used<br>
IRQF_SHARED which means you want to share your interrupt line. Also check<br>
whether you really want to share your interrupt line and also if you want<br>
to use "(void *)(adc_irq_handler)" as the unique identification.<br>
<br>
HTH!<br>
<br>
Regards<br>
Mayur<br>
<br>
On Tue, Feb 7, 2012 at 7:45 PM, nils.stec <<a href="mailto:nils.stec@googlemail.com">nils.stec@googlemail.com</a>> wrote:<br>
<br>
> Hi,<br>
><br>
> atm I'm writing a kernel module for an embedded ARM device.<br>
> This module uses IRQ9.<br>
><br>
> If i remove the module, the kernel tells me that:<br>
><br>
> ------------[ cut here ]------------<br>
> WARNING: at kernel/irq/manage.c:858 __free_irq+0x84/0x154()<br>
> Trying to free already-free IRQ 9<br>
> Modules linked in: adc_demo_irq(P-) g_ether pegasus mii<br>
> [<c0028794>] (unwind_backtrace+0x0/0xd0) from [<c003b504>]<br>
> (warn_slowpath_common+0x48/0x60)<br>
> [<c003b504>] (warn_slowpath_common+0x48/0x60) from [<c003b554>]<br>
> (warn_slowpath_fmt+0x24/0x30)<br>
> [<c003b554>] (warn_slowpath_fmt+0x24/0x30) from [<c005fa00>]<br>
> (__free_irq+0x84/0x154)<br>
> [<c005fa00>] (__free_irq+0x84/0x154) from [<c005fb0c>]<br>
> (free_irq+0x3c/0x5c)<br>
> [<c005fb0c>] (free_irq+0x3c/0x5c) from [<bf01e18c>]<br>
> (cleanup_module+0x4c/0x60 [adc_demo_irq])<br>
> [<bf01e18c>] (cleanup_module+0x4c/0x60 [adc_demo_irq]) from [<c005b898>]<br>
> (sys_delete_module+0x1c4/0x238)<br>
> [<c005b898>] (sys_delete_module+0x1c4/0x238) from [<c0022dc0>]<br>
> (ret_fast_syscall+0x0/0x28)<br>
> ---[ end trace 60d7a16d878ac0b3 ]---<br>
> adc testing module removed<br>
> ------------[ cut here ]------------<br>
><br>
> The message "adc testing module removed" comes from my module **after**free_irq() via printk, so the module exit routine works till the end.<br>
><br>
> This is my code (only the IRQ related part):<br>
><br>
> irqreturn_t adc_irq_handler(int irq, void *dev_id) {<br>
><br>
> ... do someting ...<br>
><br>
> return IRQ_HANDLED;<br>
> }<br>
><br>
> int init_module(void) {<br>
> int32_t retval;<br>
> ...<br>
> retval = request_irq(ADC_IRQ, adc_irq_handler, IRQF_SHARED, "lpc313x<br>
> adc irq", (void *)(adc_irq_handler));<br>
> ...<br>
> return retval;<br>
> }<br>
><br>
> void cleanup_module(void) {<br>
> ...<br>
> free_irq(ADC_IRQ, NULL); /* remove interrupt handler */<br>
> ...<br>
> return;<br>
> }<br>
><br>
><br>
> I hope anyone of you can help me with that problem. If you need more<br>
> information, i'll send it<br>
><br>
> Greetings,<br>
> Nils<br>
><br>
> _______________________________________________<br>
> Kernelnewbies mailing list<br>
> <a href="mailto:Kernelnewbies@kernelnewbies.org">Kernelnewbies@kernelnewbies.org</a><br>
> <a href="http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies" target="_blank">http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies</a><br>
><br>
><br>
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<br>
Message: 2<br>
Date: Tue, 7 Feb 2012 07:07:50 -0800<br>
From: Greg KH <<a href="mailto:greg@kroah.com">greg@kroah.com</a>><br>
Subject: Re: request_firmware question<br>
To: anish kumar <<a href="mailto:anish198519851985@gmail.com">anish198519851985@gmail.com</a>><br>
Cc: <a href="mailto:Kernelnewbies@kernelnewbies.org">Kernelnewbies@kernelnewbies.org</a><br>
Message-ID: <<a href="mailto:20120207150750.GA7583@kroah.com">20120207150750.GA7583@kroah.com</a>><br>
Content-Type: text/plain; charset=us-ascii<br>
<br>
On Tue, Feb 07, 2012 at 12:51:42AM -0800, anish kumar wrote:<br>
> Hi,<br>
><br>
> Now I have switched to using request_firmware api<br>
> and after using firmware, memory is being released.<br>
> Does it save kernel memory compare to case when<br>
> I am having a having a local static firmware buffer(very big)<br>
> from which I used to get the firmware and write it<br>
> to the chip?<br>
><br>
> As I know request_firmware api has several advantages<br>
> but what I want to know is the advantages related<br>
> to kernel memory footprint.<br>
<br>
Yes it is, as well as using the "proper" api for firmware loading, which<br>
means it fits into the rest of the kernel correctly.<br>
<br>
Also, no new drivers will be accepted that have static firmware blobs.<br>
<br>
greg k-h<br>
<br>
<br>
<br>
------------------------------<br>
<br>
Message: 3<br>
Date: Tue, 07 Feb 2012 16:40:13 +0100<br>
From: Bernd Petrovitsch <<a href="mailto:bernd@petrovitsch.priv.at">bernd@petrovitsch.priv.at</a>><br>
Subject: Re: fork() and exec()<br>
To: Vijay Chauhan <<a href="mailto:kernel.vijay@gmail.com">kernel.vijay@gmail.com</a>><br>
Cc: <a href="mailto:kernelnewbies@kernelnewbies.org">kernelnewbies@kernelnewbies.org</a><br>
Message-ID: <1328629213.25984.123.camel@thorin><br>
Content-Type: text/plain; charset="UTF-8"<br>
<br>
On Die, 2012-02-07 at 00:38 +0530, Vijay Chauhan wrote:<br>
> Hi List,<br>
><br>
> I am learning Linux and trying to understand exec and fork function.<br>
> execl says that it overlays the running address space. What does it mean?<br>
><br>
> I created the following program and used top command with<br>
> intentionally wrong arguments:<br>
><br>
> #include<stdio.h><br>
> #include<unistd.h><br>
> #include<sys/types.h><br>
> #include<stdlib.h><br>
><br>
> int main(){<br>
> int a = -1;<br>
> if(fork()==0){<br>
> printf("Inside child\n");<br>
> printf("child pid=%d, parentid=%d\n", getpid(), getppid());<br>
> execl("/usr/bin/top", "/usr/bin/top", ">/dev/null" ,(char*)0 );<br>
<br>
You get here only if the execl() as such fails.<br>
<br>
> scanf("inside child provide a %d", &a);<br>
<br>
You should check the return value here if you actually got a matching<br>
parameter.<br>
scanf() is actually a function to be avoided.<br>
<br>
> printf("Inside child a=%d\n", a);<br>
> exit(1);<br>
> } else {<br>
> printf("Inside parent, going to wait\n");<br>
> printf("my pid=%d, parentid=%d\n", getpid(), getppid());<br>
> scanf("input parent %d\n", &a);<br>
<br>
You should check the return value here if you actually got a matching<br>
parameter.<br>
scanf() is actually a function to be avoided.<br>
<br>
> wait(NULL);<br>
<br>
You should check the return value here to know why "wait()" returns.<br>
<br>
> printf("Wait over\n");<br>
> printf("Inside parent a=%d\n", a);<br>
> }<br>
> return 0;<br>
> }<br>
<br>
Bernd<br>
--<br>
Bernd Petrovitsch Email : <a href="mailto:bernd@petrovitsch.priv.at">bernd@petrovitsch.priv.at</a><br>
LUGA : <a href="http://www.luga.at" target="_blank">http://www.luga.at</a><br>
<br>
<br>
<br>
<br>
------------------------------<br>
<br>
Message: 4<br>
Date: Tue, 7 Feb 2012 22:10:46 +0530<br>
From: Kartik Singhal <<a href="mailto:kartiksinghal@gmail.com">kartiksinghal@gmail.com</a>><br>
Subject: Re: make config errors while building kernel on Fedora 16<br>
To: Mulyadi Santosa <<a href="mailto:mulyadi.santosa@gmail.com">mulyadi.santosa@gmail.com</a>><br>
Cc: <a href="mailto:Kernelnewbies@kernelnewbies.org">Kernelnewbies@kernelnewbies.org</a><br>
Message-ID:<br>
<<a href="mailto:CAAY3Td5UJYmtqM5mzkBHug5bfMx0q5CoBd5CowtDNTdVrTORTQ@mail.gmail.com">CAAY3Td5UJYmtqM5mzkBHug5bfMx0q5CoBd5CowtDNTdVrTORTQ@mail.gmail.com</a>><br>
Content-Type: text/plain; charset="utf-8"<br>
<br>
On Mon, Feb 6, 2012 at 1:05 PM, Mulyadi Santosa<br>
<<a href="mailto:mulyadi.santosa@gmail.com">mulyadi.santosa@gmail.com</a>>wrote:<br>
<br>
> have you check their checksums?<br>
<br>
<br>
Is there a way to verify the checksums for git clones as in my case?<br>
<br>
--<br>
Kartik<br>
<a href="http://k4rtik.wordpress.com/" target="_blank">http://k4rtik.wordpress.com/</a><br>
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