Re: [Intel-gfx] [PATCH] drm/i915: move intel_hws_csb_write_index() out of i915_drv.h

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 08/02/2022 17:16, Jani Nikula wrote:
> Underscore prefix the index macros, and place
> INTEL_HWS_CSB_WRITE_INDEX() as a macro next to them, to declutter
> i915_drv.h.
> 
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>   drivers/gpu/drm/i915/gt/intel_engine.h               | 6 ++++--
>   drivers/gpu/drm/i915/gt/intel_execlists_submission.c | 2 +-
>   drivers/gpu/drm/i915/gvt/execlist.c                  | 2 +-
>   drivers/gpu/drm/i915/i915_drv.h                      | 8 --------
>   4 files changed, 6 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine.h b/drivers/gpu/drm/i915/gt/intel_engine.h
> index 0e353d8c2bc8..faf26ed37d01 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine.h
> +++ b/drivers/gpu/drm/i915/gt/intel_engine.h
> @@ -180,8 +180,10 @@ intel_write_status_page(struct intel_engine_cs *engine, int reg, u32 value)
>   #define I915_GEM_HWS_SCRATCH		0x80
>   
>   #define I915_HWS_CSB_BUF0_INDEX		0x10
> -#define I915_HWS_CSB_WRITE_INDEX	0x1f
> -#define ICL_HWS_CSB_WRITE_INDEX		0x2f
> +#define _I915_HWS_CSB_WRITE_INDEX	0x1f
> +#define _ICL_HWS_CSB_WRITE_INDEX		0x2f

I don't quite get why would these two be the only ones which need 
underscore prefix?

> +#define INTEL_HWS_CSB_WRITE_INDEX(__i915) \
> +	(GRAPHICS_VER(__i915) >= 11 ? _ICL_HWS_CSB_WRITE_INDEX : _I915_HWS_CSB_WRITE_INDEX)

Secondly, on the point of the best new home for it, it is better than 
i915_drv.h that is for sure. But is it the best I am not sure.

CSB in general seems to have identity crisis with some bits being in 
intel_engine.h, but some also in intel_lrc.h. Neither seems completely 
right to me. It should all really be in intel_execlists_submission.h. 
Unless someone would then make an argument the latter is about the i915 
execlists scheduler backend and shouldn't strictly contain execlists 
hardware definitions like the CSB layout. Still, at the moment for me it 
feels like a better place than either intel_engine.h or intel_lrc.h.

And probably all three execlists_ prefix functions from intel_engine.h 
should go to intel_execlists_submission.h as well.

We can leave the ramblings for later and for now just explain why 
underscores please, depending on which r-b or not.

Regards,

Tvrtko

>   
>   void intel_engine_stop(struct intel_engine_cs *engine);
>   void intel_engine_cleanup(struct intel_engine_cs *engine);
> diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> index 9bb7c863172f..961d795220a3 100644
> --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> @@ -3503,7 +3503,7 @@ int intel_execlists_submission_setup(struct intel_engine_cs *engine)
>   		(u64 *)&engine->status_page.addr[I915_HWS_CSB_BUF0_INDEX];
>   
>   	execlists->csb_write =
> -		&engine->status_page.addr[intel_hws_csb_write_index(i915)];
> +		&engine->status_page.addr[INTEL_HWS_CSB_WRITE_INDEX(i915)];
>   
>   	if (GRAPHICS_VER(i915) < 11)
>   		execlists->csb_size = GEN8_CSB_ENTRIES;
> diff --git a/drivers/gpu/drm/i915/gvt/execlist.c b/drivers/gpu/drm/i915/gvt/execlist.c
> index c8dcda6d4f0d..66d354c4195b 100644
> --- a/drivers/gpu/drm/i915/gvt/execlist.c
> +++ b/drivers/gpu/drm/i915/gvt/execlist.c
> @@ -163,7 +163,7 @@ static void emulate_csb_update(struct intel_vgpu_execlist *execlist,
>   					       hwsp_gpa + I915_HWS_CSB_BUF0_INDEX * 4 + write_pointer * 8,
>   					       status, 8);
>   		intel_gvt_hypervisor_write_gpa(vgpu,
> -					       hwsp_gpa + intel_hws_csb_write_index(execlist->engine->i915) * 4,
> +					       hwsp_gpa + INTEL_HWS_CSB_WRITE_INDEX(execlist->engine->i915) * 4,
>   					       &write_pointer, 4);
>   	}
>   
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 8c1706fd81f9..05656cc738d1 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1739,14 +1739,6 @@ mkwrite_device_info(struct drm_i915_private *dev_priv)
>   	return (struct intel_device_info *)INTEL_INFO(dev_priv);
>   }
>   
> -static inline int intel_hws_csb_write_index(struct drm_i915_private *i915)
> -{
> -	if (GRAPHICS_VER(i915) >= 11)
> -		return ICL_HWS_CSB_WRITE_INDEX;
> -	else
> -		return I915_HWS_CSB_WRITE_INDEX;
> -}
> -
>   static inline enum i915_map_type
>   i915_coherent_map_type(struct drm_i915_private *i915,
>   		       struct drm_i915_gem_object *obj, bool always_coherent)