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

Daniel Thompson
2020-06-11T10:52:43Z

On Wed, Jun 10, 2020 at 11:42:43PM -0700, Joe Perches wrote:
> On Thu, 2020-06-11 at 08:26 +0200, Greg Kroah-Hartman wrote:
> > On Wed, Jun 10, 2020 at 01:23:56PM -0700, Joe Perches wrote:
> > > 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;
> >
> > Ok, and will this proposal be able to handle stuff like this?
>
> Yes, that's the entire point.

Currently I think there not enough "levels" to map something like
drm.debug to the new dyn dbg feature. I don't think it is intrinsic
but I couldn't find the bit of the code where the 5-bit level in struct
_ddebug is converted from a mask to a bit number and vice-versa.

Daniel.