[Intel-gfx] [PATCH 2/4] drm/i915: Introduce private PAT management

[Chris Wilson]

Quoting Zhi Wang (2017-09-05 20:58:25)
> The private PAT management is to support PPAT entry manipulation. Two
> APIs are introduced for dynamically managing PPAT entries: intel_ppat_get
> and intel_ppat_put.
> 
> intel_ppat_get will search for an existing PPAT entry which perfectly
> matches the required PPAT value. If not, it will try to allocate or
> return a partially matched PPAT entry if there is any available PPAT
> indexes or not.
> 
> intel_ppat_put will put back the PPAT entry which comes from
> intel_ppat_get. If it's dynamically allocated, the reference count will
> be decreased. If the reference count turns into zero, the PPAT index is
> freed again.
> 
> Besides, another two callbacks are introduced to support the private PAT
> management framework. One is ppat->update_hw(), which writes the PPAT
> configurations in ppat->entries into HW. Another one is ppat->match, which
> will return a score to show how two PPAT values match with each other.
> 
> v7:
> 
> - Keep all the register writes unchanged in this patch. (Joonas)
> 
> v6:
> 
> - Address all comments from Chris:
> http://www.spinics.net/lists/intel-gfx/msg136850.html
> 
> - Address all comments from Joonas:
> http://www.spinics.net/lists/intel-gfx/msg136845.html
> 
> v5:
> 
> - Add check and warnnings for those platforms which don't have PPAT.
> 
> v3:
> 
> - Introduce dirty bitmap for PPAT registers. (Chris)
> - Change the name of the pointer "dev_priv" to "i915". (Chris)
> - intel_ppat_{get, put} returns/takes a const intel_ppat_entry *. (Chris)
> 
> v2:
> 
> - API re-design. (Chris)
> 
> Cc: Ben Widawsky <benjamin.widawsky at intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Signed-off-by: Zhi Wang <zhi.a.wang at intel.com>

> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
> index b4e3aa7..e10ca89 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.h
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
> @@ -143,6 +143,11 @@ typedef u64 gen8_ppgtt_pml4e_t;
>  #define GEN8_PPAT_ELLC_OVERRIDE                (0<<2)
>  #define GEN8_PPAT(i, x)                        ((u64)(x) << ((i) * 8))
>  
> +#define GEN8_PPAT_GET_CA(x) ((x) & 3)
> +#define GEN8_PPAT_GET_TC(x) ((x) & (3 << 2))
> +#define GEN8_PPAT_GET_AGE(x) ((x) & (3 << 4))
> +#define CHV_PPAT_GET_SNOOP(x) ((x) & (1 << 6))

One day we will use bitfield.h to our advantage.
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris