On Wed, Dec 28, 2011 at 8:22 PM, autif khan <autif.mlist@gmail.com> wrote:

Hi Chetan,

I was wondering if switching to unlocked_ioctl() fixed the issue.

I will be developing a hardware driver and would like to know how you made out. Please let me know if the 'cmd' is passed correctly.

Thanks for sharing.

Autif

Hi Autif, Please go through the link: http://lwn.net/Articles/119652/ Problem with my dummy driver was that i am using unlocked_ioctl, but defined the ioctl function with wrong syntax (i.e. with syntax of normal ioctl function.) Thanks, Chetan Nanda

On Tue, Dec 27, 2011 at 10:34 PM, Chetan Nanda <chetannanda@gmail.com> wrote:

...

On Tue, Dec 27, 2011 at 11:25 PM, Dave Hylands <dhylands@gmail.com>

wrote:

...

...

Hi Chetan,

On Tue, Dec 27, 2011 at 3:39 AM, Chetan Nanda <chetannanda@gmail.com> wrote:

...

Hi All,

I am facing a strange issue with the ioctl commands, and not able to find what wrong I am doing. I am trying with a dummy kernel driver and implemented ioctl command

as

...

...

follow:

in my_ioctl.h #define READHWREG_MAGIC_NUMBER 0x15 #define READHWREG_CAM_READPE _IOR(READHWREG_MAGIC_NUMBER, 1, int*)

But the value of 'READHWREG_CAM_READPE' is comes out to be different in userspace (in the application) and kernel space (in the driver).

In userspace I used ioctl as ... printf("\ncommand %x \n",READHWREG_CAM_READPE); <-- command 80041501 error = ioctl(g_DevFileId, READHWREG_CAM_READPE); ..

In kernel space

int readHwReg_ioctl(struct inode *node, struct file *filp, unsigned int cmd, unsigned long arg) { ... printk("\n%d %s cmd = %x\n",__LINE__,__FUNCTION__,cmd); <--- cmd = bee6a9d4

Back in 2.6.36, the ioctl member of the struct file_operations structure (which took 4 arguments) was finally deprecated, replaced with unlocked_ioctl (which only takes 3 arguments).

If you just renamed and ignored the compiler warnings, then that explains your problem.

Thanks Dave for pointing out 'unlocked_ioctl' I come across this link: http://lwn.net/Articles/119652/

...

-- Dave Hylands Shuswap, BC, Canada http://www.davehylands.com

Thanks, Chetan Nanda

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