[Intel-gfx] [RFC 1/4] drm/i915: Add Display Gen info.

[Lucas De Marchi]

On Wed, Oct 31, 2018 at 10:13:43AM +0200, Jani Nikula wrote:
> On Tue, 30 Oct 2018, Lucas De Marchi <lucas.de.marchi at gmail.com> wrote:
> > On Tue, Oct 30, 2018 at 11:52:30AM +0200, Jani Nikula wrote:
> >> On Mon, 29 Oct 2018, Rodrigo Vivi <rodrigo.vivi at intel.com> wrote:
> >> > +#define IS_DISPLAY_GEN2(dev_priv)	(!!((dev_priv)->info.display_gen_mask \
> >> > +					    & BIT(2)))
> >> > +#define IS_DISPLAY_GEN3(dev_priv)	(!!((dev_priv)->info.display_gen_mask \
> >> > +					    & BIT(3)))
> >> > +#define IS_DISPLAY_GEN4(dev_priv)	(!!((dev_priv)->info.display_gen_mask \
> >> > +					    & BIT(4)))
> >> > +#define IS_DISPLAY_GEN5(dev_priv)	(!!((dev_priv)->info.display_gen_mask \
> >> > +					    & BIT(5)))
> >> > +#define IS_DISPLAY_GEN6(dev_priv)	(!!((dev_priv)->info.display_gen_mask \
> >> > +					    & BIT(6)))
> >> > +#define IS_DISPLAY_GEN7(dev_priv)	(!!((dev_priv)->info.display_gen_mask \
> >> > +					    & BIT(7)))
> >> > +#define IS_DISPLAY_GEN8(dev_priv)	(!!((dev_priv)->info.display_gen_mask \
> >> > +					    & BIT(8)))
> >> > +#define IS_DISPLAY_GEN9(dev_priv)	(!!((dev_priv)->info.display_gen_mask \
> >> > +					    & BIT(9)))
> >> > +#define IS_DISPLAY_GEN10(dev_priv)	(!!((dev_priv)->info.display_gen_mask \
> >> > +					    & BIT(10)))
> >> > +#define IS_DISPLAY_GEN11(dev_priv)	(!!((dev_priv)->info.display_gen_mask \
> >> > +					    & BIT(11)))
> >> 
> >> I know this is the same pattern as in IS_GEN<N> above, but shouldn't the
> >> compiler end up with the same result if these were simply:
> >> 
> >> #define IS_DISPLAY_GEN2(dev_priv) IS_DISPLAY_GEN(dev_priv, 2, 2)
> >
> >
> > humn... maybe this is too magic, but it works for me and I didn't add any additional
> > macro to the kernel to implement it :)
> >
> > [CI, DON'T TEST THIS] diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> > [CI, DON'T TEST THIS] index 554627dc623c..02a8b51fd733 100644
> > [CI, DON'T TEST THIS] --- a/drivers/gpu/drm/i915/i915_drv.h
> > [CI, DON'T TEST THIS] +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -2385,9 +2385,15 @@ intel_info(const struct drm_i915_private *dev_priv)
> >  	GENMASK((e) - 1, (s) - 1))
> >  
> >  /* Returns true if Gen is in inclusive range [Start, End] */
> > -#define IS_GEN(dev_priv, s, e) \
> > +#define _IS_GEN_ARG2(dev_priv, s, e) \
> >  	(!!((dev_priv)->info.gen_mask & INTEL_GEN_MASK((s), (e))))
> >  
> > +#define _IS_GEN_ARG1(dev_priv, g) \
> > +	(!!((dev_priv)->info.gen_mask & BIT((g) - 1)))
> > +
> > +#define IS_GEN(dev_priv, ...) \
> > +	CONCATENATE(_IS_GEN_ARG, COUNT_ARGS(__VA_ARGS__))((dev_priv), ##__VA_ARGS__)
> > +
> >  /*
> >   * Return true if revision is in range [since,until] inclusive.
> >   *
> >
> >
> > So we could use IS_GEN(dev_priv, 2) as well as IS_GEN(dev_priv, 2, 4), which IMO is very clear.
> > The same would apply for IS_DISPLAY_GEN() version. And if they generate the same code, we could
> > just change the expansion to repeat the argument.
> 
> I like this stuff. 
> 
> So I'd prefer IS_GEN(dev_priv, 2) in favor of IS_GEN2(dev_priv)
> throughout.
> 
> As long as it doesn't increase the code size too much, but this being
> macro magic I don't think it should.
> 
> Care to cook up a patch against current tip to make IS_GEN() take 1 or 2
> args? If I read the above right, you'll get a build error for using
> IS_GEN(dev_priv, 1, 2, 3), is that correct?

Correct.  I'll prepare a patch for that so we can discuss on the approach
with a concrete example.

Lucas De Marchi

> 
> BR,
> Jani.
> 
> 
> -- 
> Jani Nikula, Intel Open Source Graphics Center