Re: [PATCH 1/2] drm/i915: Introduce INTEL_GEN_MASK

[Jani Nikula <jani.nikula@intel.com>]

On Fri, 08 Sep 2017, Joonas Lahtinen <joonas.lahtinen@linux.intel.com> wrote:
> Split INTEL_GEN_MASK out of IS_GEN macro, and make it usable
> within static declarations (unlike combound statements).
>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h | 22 ++++++++++------------
>  1 file changed, 10 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 63ca2ffcafef..c3f9d7d7b146 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2873,23 +2873,21 @@ intel_info(const struct drm_i915_private *dev_priv)
>  #define INTEL_REVID(dev_priv)	((dev_priv)->drm.pdev->revision)
>  
>  #define GEN_FOREVER (0)
> +
> +#define INTEL_GEN_MASK(s, e) ( \
> +        BUILD_BUG_ON_ZERO(!__builtin_constant_p(s)) + \
> +        BUILD_BUG_ON_ZERO(!__builtin_constant_p(e)) + \
> +        GENMASK((e) != GEN_FOREVER ? (e) - 1 : BITS_PER_LONG - 1, \
> +	        (s) != GEN_FOREVER ? (s) - 1 : 0) \

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

but I'd really like a patch on top to remove the -1 from here and
info->gen_mask.

> +)
> +
>  /*
>   * Returns true if Gen is in inclusive range [Start, End].
>   *
>   * Use GEN_FOREVER for unbound start and or end.
>   */
> -#define IS_GEN(dev_priv, s, e) ({ \
> -	unsigned int __s = (s), __e = (e); \
> -	BUILD_BUG_ON(!__builtin_constant_p(s)); \
> -	BUILD_BUG_ON(!__builtin_constant_p(e)); \
> -	if ((__s) != GEN_FOREVER) \
> -		__s = (s) - 1; \
> -	if ((__e) == GEN_FOREVER) \
> -		__e = BITS_PER_LONG - 1; \
> -	else \
> -		__e = (e) - 1; \
> -	!!((dev_priv)->info.gen_mask & GENMASK((__e), (__s))); \
> -})
> +#define IS_GEN(dev_priv, s, e) \
> +	(!!((dev_priv)->info.gen_mask & INTEL_GEN_MASK((s), (e))))

Actually, why do we even have info->gen_mask? It'll only ever have one
bit set, and it's duplication of information. Why don't we use
BIT((dev_priv)->info.gen) here?

BR,
Jani.

>  
>  /*
>   * Return true if revision is in range [since,until] inclusive.

-- 
Jani Nikula, Intel Open Source Technology Center
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