linux-kernel - Re: [PATCH v6 4/7] drm/i915: Convert REG_GENMASK*() to fixed-width GENMASK

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Message-ID: <Z9mqUZX4H-CzqbW4@thinkpad>
Date: Tue, 18 Mar 2025 13:16:01 -0400
From: Yury Norov <yury.norov@...il.com>
To: mailhol.vincent@...adoo.fr
Cc: Lucas De Marchi <lucas.demarchi@...el.com>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Tvrtko Ursulin <tursulin@...ulin.net>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, intel-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	Andi Shyti <andi.shyti@...ux.intel.com>,
	David Laight <David.Laight@...lab.com>,
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Jani Nikula <jani.nikula@...el.com>
Subject: Re: [PATCH v6 4/7] drm/i915: Convert REG_GENMASK*() to fixed-width
 GENMASK_U*()

On Sat, Mar 08, 2025 at 01:48:51AM +0900, Vincent Mailhol via B4 Relay wrote:
> From: Lucas De Marchi <lucas.demarchi@...el.com>
> 
> Now that include/linux/bits.h implements fixed-width GENMASK_U*(), use
> them to implement the i915/xe specific macros. Converting each driver
> to use the generic macros are left for later, when/if other
> driver-specific macros are also generalized.
> 
> Signed-off-by: Lucas De Marchi <lucas.demarchi@...el.com>
> Acked-by: Jani Nikula <jani.nikula@...el.com>
> Signed-off-by: Vincent Mailhol <mailhol.vincent@...adoo.fr>
> ---
> Changelog:
> 
>   v5 -> v6:
> 
>     - No changes.
> 
>   v4 -> v5:
> 
>     - Add braket to macro names in patch description,
>       e.g. 'REG_GENMASK*' -> 'REG_GENMASK*()'
> 
>   v3 -> v4:
> 
>     - Remove the prefixes in macro parameters,
>       e.g. 'REG_GENMASK(__high, __low)' -> 'REG_GENMASK(high, low)'
> ---
>  drivers/gpu/drm/i915/i915_reg_defs.h | 108 ++++-------------------------------
>  1 file changed, 11 insertions(+), 97 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg_defs.h b/drivers/gpu/drm/i915/i915_reg_defs.h
> index e251bcc0c89f5710125bc70f07851b2cb978c89c..39e5ed9511174b8757b9201bff735fa362651b34 100644
> --- a/drivers/gpu/drm/i915/i915_reg_defs.h
> +++ b/drivers/gpu/drm/i915/i915_reg_defs.h
> @@ -9,76 +9,19 @@
>  #include <linux/bitfield.h>
>  #include <linux/bits.h>
>  
> -/**
> - * REG_BIT() - Prepare a u32 bit value
> - * @__n: 0-based bit number
> - *
> - * Local wrapper for BIT() to force u32, with compile time checks.
> - *
> - * @return: Value with bit @__n set.
> +/*
> + * Wrappers over the generic BIT_* and GENMASK_* implementations,
> + * for compatibility reasons with previous implementation
>   */
> -#define REG_BIT(__n)							\
> -	((u32)(BIT(__n) +						\
> -	       BUILD_BUG_ON_ZERO(__is_constexpr(__n) &&		\
> -				 ((__n) < 0 || (__n) > 31))))
> +#define REG_GENMASK(high, low)		GENMASK_U32(high, low)
> +#define REG_GENMASK64(high, low)	GENMASK_U64(high, low)
> +#define REG_GENMASK16(high, low)	GENMASK_U16(high, low)
> +#define REG_GENMASK8(high, low)		GENMASK_U8(high, low)

Nit. Maybe just

 #define REG_GENMASK		GENMASK_U32