Re: Reading the frame number field

On Apr 12, 2007, at 6:25 PM, Alan Stern wrote:

> On Thu, 12 Apr 2007, Danny Budik wrote:
>
>> Would it be possible to add my own constant to /usr/include/linux/
>> usbdevice_fs.h and write an underlying function that would call
>> usb_get_current_frame_number()? It
>> looks like I can add a constant say USBDEVFS_FRAMENUM in
>> usbdevice_fs.h, add new case to .../drivers/usb/core/devio.c, add a
>> function called proc_framenum
>> that would call usb_get_current_frame_number() and return the frame
>> number. Is this a reasonable and/or feasible solution?

Below is a patch to do this but I am new to Linux kernel development  
area.  Since this modifies a core usb driver, it's not compiled as a  
module rather into the kernel itself. So, is there a way for me to do  
the following without recompiling the kernel: 1) compile the driver  
by itself and 2) test the functionality of the driver with my user  
space program? Do I have to recompile the whole kernel every time I  
make a modification?
Again I'm a newbie, so if you could point me to a good resource on  
how to do this I'd greatly appreciate it.

Thanks,
Danny


linux-source-2.6.17/drivers/usb/core/devio.c
812a813,826
 > static int proc_getframenum(struct dev_state *ps, void __user *arg)
 > {
 >       int frame_number;
 >       struct usb_device *dev = ps->dev;
 >
 >       frame_number = usb_get_current_frame_number(dev);
 >
 >       if (put_user(frame_number, (int __user *)arg))
 >               return -EFAULT;
 >
 >       return 0;
 >
 > }
 >
1544a1559,1564
 >
 >       case USBDEVFS_GETFRAMENUM:
 >               snoop(&dev->dev, "%s: GETFRAMENUM\n", __FUNCTION__);
 >               ret = proc_getframenum(ps, p);
 >               break;
 >



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