Re: [RFC] Unify messaging in gadget functions

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Dec 05, 2022 at 03:13:46PM +0100, Andrzej Pietrasiewicz wrote:
> Hi Greg,
> 
> W dniu 5.12.2022 o 13:20, Greg KH pisze:
> > On Mon, Dec 05, 2022 at 01:14:21PM +0100, Andrzej Pietrasiewicz wrote:
> > > Hi All,
> > > 
> > > include/linux/usb/composite.h contains:
> > > 
> > > /* messaging utils */
> > > #define DBG(d, fmt, args...) \
> > > 	dev_dbg(&(d)->gadget->dev , fmt , ## args)
> > > #define VDBG(d, fmt, args...) \
> > > 	dev_vdbg(&(d)->gadget->dev , fmt , ## args)
> > > #define ERROR(d, fmt, args...) \
> > > 	dev_err(&(d)->gadget->dev , fmt , ## args)
> > > #define WARNING(d, fmt, args...) \
> > > 	dev_warn(&(d)->gadget->dev , fmt , ## args)
> > > #define INFO(d, fmt, args...) \
> > > 	dev_info(&(d)->gadget->dev , fmt , ## args)
> > > 
> > > Gadget functions do use these, but not consistently:
> 
> <snip>
> 
> > > Questions:
> > > 
> > > 1) Should we make them use the messaging utils consitently?
> > 
> > Yes, converting to use the dev_*() calls is good to do.
> 
> Heh, I sent this RFC to prevent learning the hard way (by actually creating
> incorrect patches), that we want to be consistent, but using dev_*() calls
> rather than composite.h utils. That's ok.
> 
> Which brings an interesting question: should the ultimate goal be to remove the
> messaging utils altogether from composite.h? It _seems_ their purpose is mainly
> to wrap dereferencing a pointer two pointers away: &(d)->gadget->dev to make
> invocations shorter. With the default of 100 columns in checkpatch nowadays it
> is maybe a less important goal? Or maybe we should prevent such long
> dereferencing by introducing helper variables just like below in
> u_audio_start_capture()?

Yes, that should be the ultimate goal.  We did that in the USB drivers a
decade or so ago, but no one spent the time to do the same for the USB
gadget code.

thanks,

greg k-h