[igt-dev] [PATCH i-g-t 09/93] lib: Add an intel_ctx wrapper struct and helpers (v4)

[Petri Latvala]

On Wed, Jun 09, 2021 at 09:41:14AM -0500, Jason Ekstrand wrote:
> On Wed, Jun 9, 2021 at 1:27 AM Petri Latvala <petri.latvala at intel.com> wrote:
> >
> > On Tue, Jun 08, 2021 at 10:30:02PM -0700, Dixit, Ashutosh wrote:
> > > On Tue, 08 Jun 2021 21:29:55 -0700, Jason Ekstrand wrote:
> > > > diff --git a/lib/intel_ctx.h b/lib/intel_ctx.h
> > > > new file mode 100644
> > > > index 00000000..79bc1154
> > > > --- /dev/null
> > > > +++ b/lib/intel_ctx.h
> > > > @@ -0,0 +1,75 @@
> > >
> > > /snip/
> > >
> > > > +/**
> > > > + * intel_ctx_cfg_t:
> > > > + * @flags: Context create flags
> > > > + * @vm: VM to inherit or 0 for using a per-context VM
> > > > + * @num_engines: Number of client-specified engines or 0 for legacy mode
> > > > + * @engines: Client-specified engines
> > > > + *
> > > > + * Represents the full configuration of an intel_ctx.
> > > > + */
> > > > +typedef struct intel_ctx_cfg {
> > > > +   uint32_t flags;
> > > > +   uint32_t vm;
> > > > +   unsigned int num_engines;
> > > > +   struct i915_engine_class_instance engines[GEM_MAX_ENGINES];
> > > > +} intel_ctx_cfg_t;
> > > > +
> > > > +intel_ctx_cfg_t intel_ctx_cfg_for_engine(unsigned int class, unsigned int inst);
> > > > +intel_ctx_cfg_t intel_ctx_cfg_all_physical(int fd);
> > > > +
> > > > +/**
> > > > + * intel_ctx_t:
> > > > + * @id: the context id/handle
> > > > + * @cfg: the config used to create this context
> > > > + *
> > > > + * Represents the full configuration of an intel_ctx.
> > > > + */
> > > > +typedef struct intel_ctx {
> > > > +   uint32_t id;
> > > > +   intel_ctx_cfg_t cfg;
> > > > +} intel_ctx_t;
> > >
> > > Just a comment about cosmetics. I am ok either way but I believe in the
> > > linux kernel (and in IGT which follows the kernel coding style) such
> > > typedefs are supposedly only to be used for "opaque" types and are
> > > generally avoided. E.g.
> > >
> > > https://yarchive.net/comp/linux/typedefs.html
> > >
> > > There are not very many instances of such typedef's in IGT, certainly not
> > > those which are this widely used.
> > >
> > > I copying Petri about this to see what he prefers, whether we should keep
> > > these typedefs or replace intel_ctx_cfg_t and intel_ctx_t with 'struct
> > > intel_ctx_cfg' and 'struct intel_ctx'.
> >
> > I have no hard preferences for this. Mostly it's a question of what
> > makes the most sense to the author, and whether gtk-doc eats it
> > without choking.
> 
> I did typedefs partly for less typing and partly because gtk-doc
> didn't like me when I was doing struct intel_ctx_cfg

Ah yes, now I remember. gtk-doc indeed likes code more when going in
that direction.

For those following along at home, never try having "union foobar" as
a function return type with gtk-doc...


-- 
Petri Latvala