[RFC] Unify messaging in gadget functions

[Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxxxx>]

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:

=> DBG() vs dev_dbg():
$ git grep DBG\( drivers/usb/gadget/function | grep -v VDBG | grep -v LDBG | wc
    138     871   11619

$ git grep dev_dbg\( drivers/usb/gadget/function | grep -v "##args" | wc
     33     151    2831

=> VDBG() vs dev_vdbg():
 git grep VDBG\( drivers/usb/gadget/function | grep -v "#define" | wc
     49     269    3954

$ git grep dev_vdbg\( drivers/usb/gadget/function | wc
      2       4     135

=> ERROR() vs dev_err():
$ git grep ERROR\( drivers/usb/gadget/function | grep -v LERROR | wc
     72     508    6560

$ git grep dev_err\( drivers/usb/gadget/function | grep -v "##args" | wc
     65     309    5527

=> WARNING() vs dev_warn():
$ git grep WARNING\( drivers/usb/gadget/function | wc
      4      28     383

$ git grep dev_warn\( drivers/usb/gadget/function | grep -v "##args" | wc
      3       6     169

=> INFO() vs dev_info():
$ git grep INFO\( drivers/usb/gadget/function  | grep -v LINFO | grep -v u_ether 
| wc
     14      64    1167

$ git grep dev_info\( drivers/usb/gadget/function | grep -v "##args" | wc
      0       0       0

Questions:

1) Should we make them use the messaging utils consitently?

2) How consistent should we become, given that some functions in the relevant
files, for example u_audio_start_capture(), sometimes (but not always) have:

	struct usb_gadget *gadget = audio_dev->gadget;
	struct device *dev = &gadget->dev;

and then they use dev_dbg(dev, ....);

If we were to use DBG(audio_dev, ....); instead, then we effectively get
dev_dbg(&audio_dev->gadget->dev, ....); after macro expansion, which means two
pointer dereferences and taking an address of the result (I'm wondering how
smart the compiler can get if such a pattern repeats several times in a
function).

3) Maybe the amount of various messages is too large in the first place
and should be reduced before any unifications?

Regards,

Andrzej