Re: [Intel-gfx] [PATCH v7 3/8] i915/gvt: use DEFINE_DYNAMIC_DEBUG_CATEGORIES to create "gvt:core:" etc categories

[jim.cromie@gmail.com]

On Fri, Sep 3, 2021 at 5:07 AM Tvrtko Ursulin
<tvrtko.ursulin@linux.intel.com> wrote:
>
>
> On 31/08/2021 21:21, Jim Cromie wrote:
> > The gvt component of this driver has ~120 pr_debugs, in 9 categories
> > quite similar to those in DRM.  Following the interface model of
> > drm.debug, add a parameter to map bits to these categorizations.
> >
> > DEFINE_DYNAMIC_DEBUG_CATEGORIES(debug_gvt, __gvt_debug,
> >       "dyndbg bitmap desc",
> >       { "gvt:cmd: ",  "command processing" },
> >       { "gvt:core: ", "core help" },
> >       { "gvt:dpy: ",  "display help" },
> >       { "gvt:el: ",   "help" },
> >       { "gvt:irq: ",  "help" },
> >       { "gvt:mm: ",   "help" },
> >       { "gvt:mmio: ", "help" },
> >       { "gvt:render: ", "help" },
> >       { "gvt:sched: " "help" });
> >

BTW, Ive dropped the help field, its already handled, dont need to clutter.


> > The actual patch has a few details different, cmd_help() macro emits
> > the initialization construct.
> >
> > if CONFIG_DRM_USE_DYNAMIC_DEBUG, then -DDYNAMIC_DEBUG_MODULE is added
> > cflags, by gvt/Makefile.
> >
> > Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
> > ---
> > v5:
> > . static decl of vector of bit->class descriptors - Emil.V
> > . relocate gvt-makefile chunk from elsewhere
> > v7:
> > . move ccflags addition up to i915/Makefile from i915/gvt
> > ---
> >   drivers/gpu/drm/i915/Makefile      |  4 ++++
> >   drivers/gpu/drm/i915/i915_params.c | 35 ++++++++++++++++++++++++++++++
>
> Can this work if put under gvt/ or at least intel_gvt.h|c?
>

I thought it belonged here more, at least according to the name of the
config.var

CONFIG_DRM_USE_DYNAMIC_DEBUG.

I suppose its not a great name, its narrow purpose is to swap
drm-debug api to use dyndbg.   drm-evrything already "uses"
dyndbg if CONFIG_DYNAMIC_DEBUG=y, those gvt/pr_debugs in particular.

Theres also CONFIG_DYNAMIC_DEBUG_CORE=y,
which drm basically ignores currently.

So with the name CONFIG_DRM_USE_DYNAMIC_DEBUG
it seemed proper to arrange for that  to be true on DD-CORE=y builds,
by adding -DDYNAMIC_DEBUG_MODULE

Does that make some sense ?
How to best resolve the frictions ?
new CONFIG names ?

> >   2 files changed, 39 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> > index 4f22cac1c49b..5a4e371a3ec2 100644
> > --- a/drivers/gpu/drm/i915/Makefile
> > +++ b/drivers/gpu/drm/i915/Makefile
> > @@ -30,6 +30,10 @@ CFLAGS_display/intel_fbdev.o = $(call cc-disable-warning, override-init)
> >
> >   subdir-ccflags-y += -I$(srctree)/$(src)
> >
> > +#ifdef CONFIG_DRM_USE_DYNAMIC_DEBUG
> > +ccflags-y += -DDYNAMIC_DEBUG_MODULE
> > +#endif
>
> Ignores whether CONFIG_DRM_I915_GVT is enabled or not?
>

not intentionally.
I think theres 2 things youre noting:

1 - make frag into gvt/Makefile
I had it there earlier, not sure why I moved it up.
maybe some confusion on proper scope of the flag.


2 - move new declaration code in i915-param.c inside the gvt ifdef

Im good with that.
I'll probably copy the ifdef wrapper down rather than move the decl up.
ie:

#if __and(IS_ENABLED(CONFIG_DRM_I915_GVT),
  IS_ENABLED(CONFIG_DRM_USE_DYNAMIC_DEBUG))

unsigned long __gvt_debug;
EXPORT_SYMBOL(__gvt_debug);


> > +
> >   # Please keep these build lists sorted!
> >
> >   # core driver code
> > diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> > index e07f4cfea63a..e645e149485e 100644
> > --- a/drivers/gpu/drm/i915/i915_params.c
> > +++ b/drivers/gpu/drm/i915/i915_params.c
> > @@ -265,3 +265,38 @@ void i915_params_free(struct i915_params *params)
> >       I915_PARAMS_FOR_EACH(FREE);
> >   #undef FREE
> >   }
> > +
> > +#ifdef CONFIG_DRM_USE_DYNAMIC_DEBUG
> > +/* todo: needs DYNAMIC_DEBUG_MODULE in some cases */
> > +
> > +unsigned long __gvt_debug;
> > +EXPORT_SYMBOL(__gvt_debug);
> > +
> > +#define _help(key)   "\t    \"" key "\"\t: help for " key "\n"
> > +
> > +#define I915_GVT_CATEGORIES(name) \
> > +     " Enable debug output via /sys/module/i915/parameters/" #name   \
> > +     ", where each bit enables a debug category.\n"                  \
> > +     _help("gvt:cmd:")                                               \
> > +     _help("gvt:core:")                                              \
> > +     _help("gvt:dpy:")                                               \
> > +     _help("gvt:el:")                                                \
> > +     _help("gvt:irq:")                                               \
> > +     _help("gvt:mm:")                                                \
> > +     _help("gvt:mmio:")                                              \
> > +     _help("gvt:render:")                                            \
> > +     _help("gvt:sched:")
> > +
> > +DEFINE_DYNAMIC_DEBUG_CATEGORIES(debug_gvt, __gvt_debug,
> > +                             I915_GVT_CATEGORIES(debug_gvt),
> > +                             _DD_cat_("gvt:cmd:"),
> > +                             _DD_cat_("gvt:core:"),
> > +                             _DD_cat_("gvt:dpy:"),
> > +                             _DD_cat_("gvt:el:"),
> > +                             _DD_cat_("gvt:irq:"),
> > +                             _DD_cat_("gvt:mm:"),
> > +                             _DD_cat_("gvt:mmio:"),
> > +                             _DD_cat_("gvt:render:"),
> > +                             _DD_cat_("gvt:sched:"));
> > +
> > +#endif
>
> So just the foundation - no actual use sites I mean? How would these be
> used from the code?
>

there are 120 pr_debug "users" :-)

no users per se, but anyone using drm.debug
/sys/module/drm/parameters/debug
might use this too.
its a bit easier than composing queries for >/proc/dyamic_debug/control




> Regards,
>
> Tvrtko