[Q] tracing/printing

Hi,

I'm writing a video capture device and have a doubt about how to
correctly print to screen.

First, I suppose I should follow the rule "don't print unless there is
something surprising to say", right?
Second, I've found I need to print in a very verbose manner
at developing stage so I should implement a debug param.
I will probably adopt videobuf2 way (like many others) of
defining a macro (dprintk or something).

However, reading the source I've found there isn't a unified
way to do this: some use printk (as defined macros), others
use v4l_xxx, others use dev_xxx.

I've adopted the latter, because I thought there could
be many devices plugged, and using dev_xxx with
the usb_device->dev helps seeing which is tracing.

I'm not really sure if it is ok so I would love to
hear some opinions about this sensible issue.

Thanks!