Dear Greg,
This is Ravi . I want to write a USB device driver for web camera .
Before i
go for this , I found a paper presented by you on the Internet, explaining
the general concepts of the usb device driver working , taking an example of
" usb- skeleton.c " . It was very useful to all of the new driver writers .
In that html documentaion I found that whenever we do
"usb_submit_urb(urb) ",
the driver will sumbit the initialized urb structure to the device . But if u
look at the implementation of " usb_submit_urb() " in " usb.c " , then you'll
come across the statements like the following ,
int usb_submit_urb(struct urb *urb)
{
if (urb && urb->dev && urb->dev->bus && urb->dev->bus->op)
return urb->dev->bus->op->submit_urb(urb);
else
return -ENODEV;
}
Here the driver is internally making a call to "submit_urb() " ,
which is a
member of the " usb_operations " structure . But I don't know how and where
the " op " object of type " usb_operations " structure, is initialized to
call " submit_urb() " function .
You please go through this , and please try to clear my doubt .
Waiting for ur reply ,
N Ravi
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