Re: [PATCH v3 6/7] venus: Make debug infrastructure more flexible

[Joe Perches <joe@perches.com>]

On Wed, 2020-06-10 at 12:49 -0700, Joe Perches wrote:
> On Wed, 2020-06-10 at 15:37 +0200, Greg Kroah-Hartman wrote:
> > Please work with the infrastructure we have, we have spent a lot of time
> > and effort to make it uniform to make it easier for users and
> > developers.
> 
> Not quite.
> 
> This lack of debug grouping by type has been a
> _long_ standing issue with drivers.
> 
> > Don't regress and try to make driver-specific ways of doing
> > things, that way lies madness...
> 
> It's not driver specific, it allows driver developers to
> better isolate various debug states instead of keeping
> lists of specific debug messages and enabling them
> individually.

For instance, look at the homebrew content in
drivers/gpu/drm/drm_print.c that does _not_ use
dynamic_debug.

MODULE_PARM_DESC(debug, "Enable debug output, where each bit enables a debug category.\n"
"\t\tBit 0 (0x01)  will enable CORE messages (drm core code)\n"
"\t\tBit 1 (0x02)  will enable DRIVER messages (drm controller code)\n"
"\t\tBit 2 (0x04)  will enable KMS messages (modesetting code)\n"
"\t\tBit 3 (0x08)  will enable PRIME messages (prime code)\n"
"\t\tBit 4 (0x10)  will enable ATOMIC messages (atomic code)\n"
"\t\tBit 5 (0x20)  will enable VBL messages (vblank code)\n"
"\t\tBit 7 (0x80)  will enable LEASE messages (leasing code)\n"
"\t\tBit 8 (0x100) will enable DP messages (displayport code)");
module_param_named(debug, __drm_debug, int, 0600);

void drm_dev_dbg(const struct device *dev, enum drm_debug_category category,
		 const char *format, ...)
{
	struct va_format vaf;
	va_list args;

	if (!drm_debug_enabled(category))
		return;