Re: [PATCH] Add support for SMSC UFX6000/7000 USB display adapters

On Fri, Aug 12, 2011 at 12:06:55PM -0700, Bernie Thompson wrote:

On Fri, Aug 12, 2011 at 8:56 AM, Greg KH [off-list ref] wrote:

    You can do the same for your calls to pr_debug() and other pr_* calls.
    If you note in the header file for those functions, it suggests that
    drivers should always call the dev_* versions instead of teh "raw" pr_*
    functions, as you do have access to a struct device within your driver.


A little background from udlfb: we weren't able to stick with dev_* calls 100%,
because udlfb needed to survive USB device removal and the freeing of the
USB-initiated device structure. This is because the framebuffer device needed
to outlive it if a client was holding on to it.  In other words, it's born a
two-headed beast (usb and fbdev), but the two faces of the device are killed
off independently based on remaining ref counts.  So there are prints in there
which will fault if converted to dev_* without this in mind.

Because of this, we had originally created our own dl_* wrapper around the pr_
macros.

Then a later patch initiated by Paul (fbdev maintainer) changed those to
uncustomized pr_ macros with a goal of uniformity with other drivers.  And that
code is what SMSC started from.

So there's some complexity behind the choices here.  It might be good to keep
common strategies between udlfb and smsc's driver, as the issues to consider
are the same.

Ok, thanks for the background information, that makes sense.

But for stuff like the usb probe() call, that should always be dev_* as
you really do have a proper pointer.  So when you do have a valid struct
device, you should use it.

Although a lot of the pr_info() calls should be downgraded to pr_debug()
I imagine, to keep things from being so noisy.

thanks,

greg k-h