Re: [Intel-gfx] [CI 1/2] drm/i915/step: Add macro magic for handling steps

["Srivatsa, Anusha" <anusha.srivatsa@intel.com>]

> -----Original Message-----
> From: Jani Nikula <jani.nikula@linux.intel.com>
> Sent: Thursday, August 12, 2021 2:59 AM
> To: Srivatsa, Anusha <anusha.srivatsa@intel.com>; intel-
> gfx@lists.freedesktop.org
> Cc: Roper, Matthew D <matthew.d.roper@intel.com>; De Marchi, Lucas
> <lucas.demarchi@intel.com>
> Subject: Re: [Intel-gfx] [CI 1/2] drm/i915/step: Add macro magic for handling
> steps
> 
> On Mon, 19 Jul 2021, Anusha Srivatsa <anusha.srivatsa@intel.com> wrote:
> > With the addition of stepping info for all platforms, lets use macros
> > for handling them and autogenerating code for all steps at a time.
> >
> > Suggested-by: Matt Roper <matthew.d.roper@intel.com>
> > Cc: Lucas De Marchi <lucas.demarchi@intel.com>
> > Signed-off-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
> > Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_step.c | 14 ++++++++++++
> > drivers/gpu/drm/i915/intel_step.h | 37 +++++++++++++++++++------------
> >  2 files changed, 37 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_step.c
> > b/drivers/gpu/drm/i915/intel_step.c
> > index 9fcf17708cc8..d150d138e889 100644
> > --- a/drivers/gpu/drm/i915/intel_step.c
> > +++ b/drivers/gpu/drm/i915/intel_step.c
> > @@ -182,3 +182,17 @@ void intel_step_init(struct drm_i915_private
> > *i915)
> >
> >  	RUNTIME_INFO(i915)->step = step;
> >  }
> > +
> > +#define STEP_NAME_CASE(name)	\
> > +	(case STEP_##name:	\
> > +		return #name)
> > +
> > +const char *intel_step_name(enum intel_step step) {
> > +	switch (step) {
> > +	STEP_NAME_LIST(STEP_NAME_CASE);
> > +
> > +	default:
> > +		return "**";
> > +	}
> > +}
> > diff --git a/drivers/gpu/drm/i915/intel_step.h
> > b/drivers/gpu/drm/i915/intel_step.h
> > index 88a77159703e..f6641e2a3c77 100644
> > --- a/drivers/gpu/drm/i915/intel_step.h
> > +++ b/drivers/gpu/drm/i915/intel_step.h
> > @@ -15,30 +15,39 @@ struct intel_step_info {
> >  	u8 display_step;
> >  };
> >
> > +#define STEP_ENUM_VAL(name)  STEP_##name,
> > +
> > +#define STEP_NAME_LIST(func)		\
> > +	func(A0)			\
> > +	func(A1)			\
> > +	func(A2)			\
> > +	func(B0)			\
> > +	func(B1)			\
> > +	func(B2)			\
> > +	func(C0)			\
> > +	func(C1)			\
> > +	func(D0)			\
> > +	func(D1)			\
> > +	func(E0)			\
> > +	func(F0)			\
> > +	func(G0)			\
> > +	func(H0)			\
> > +	func(I0)			\
> > +	func(I1)			\
> > +	func(J0)
> > +
> >  /*
> >   * Symbolic steppings that do not match the hardware. These are valid
> both as gt
> >   * and display steppings as symbolic names.
> >   */
> >  enum intel_step {
> >  	STEP_NONE = 0,
> > -	STEP_A0,
> > -	STEP_A2,
> > -	STEP_B0,
> > -	STEP_B1,
> > -	STEP_C0,
> > -	STEP_D0,
> > -	STEP_D1,
> > -	STEP_E0,
> > -	STEP_F0,
> > -	STEP_G0,
> > -	STEP_H0,
> > -	STEP_I0,
> > -	STEP_I1,
> > -	STEP_J0,
> > +	STEP_NAME_LIST(STEP_ENUM_VAL)
> >  	STEP_FUTURE,
> >  	STEP_FOREVER,
> >  };
> 
> It's been merged already, and so be it.
> 
> I'll just note that the main reason I don't like adding this kind of macro
> abstractions is that it throws off source code tagging tools like ctags and gnu
> global. I can no longer navigate the definition and all the references of
> STEP_* using the tools, and it degenerates to git grep which is much worse as
> it doesn't know about C syntax or semantics. It's not always about how the
> code looks, it's also about how people can navigate the code base.

Had not considered that :-/ will keep this in mind from now on.
Thanks for the feedback.

Anusha
> BR,
> Jani.
> 
> 
> >
> >  void intel_step_init(struct drm_i915_private *i915);
> > +const char *intel_step_name(enum intel_step step);
> >
> >  #endif /* __INTEL_STEP_H__ */
> 
> --
> Jani Nikula, Intel Open Source Graphics Center