Dear Simon Glass,
In message AANLkTik7dQqC8-m5pmXqiT1ObPhKTPTPbqu=TucMAk=n@mail.gmail.com you wrote:
There is a great big DEBUG define which determines whether debug() is a printf() or a nop. This is used by various modules to make them more verbose which is helpful sometimes.
Some modules have their own finer control over this, for example USB_DEBUG in common/usb.c. Also:
This is usually code that was imported from other projects (like the Linux kernel) where their debug facilities were left in place to make later updates easier.
Recently I enabled DEBUG and got rather a lot of output, enough that it took hours to boot a kernel (every MMC block printed a nice message from the GPIO driver). I understand that creating these local DEBUG macros is frowned upon, but without this it tends to make the U-Boot-wide DEBUG setting so verbose as to be useless. It also means that every potentially verbose module needs an '#undef DEBUG' at the top, which means the global flag is overridden.
No, this is not the way we usually work.
Can I suggest perhaps a way of allowing some sort of granularity in the design, rather than just relying on hacking in DEBUG in each file? What is the recommended approach, please?
The normal method is to NOT enable DEBUG globally, but only in the source files which you really want to debug. You can do this either by board-specific compiler flags, or (usually easier) by simply adding a "#define DEBUG" in the respective source files (before the first #include line).
If you need a fancier approach please go on and implement it. Patches welcome.
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Best regards,
Wolfgang Denk