binary constants (was: Re: [PATCH v3] drm/dp: Add Additional DP2 Headers)

Jani Nikula jani.nikula at intel.com
Thu Feb 3 11:58:00 UTC 2022


On Mon, 27 Sep 2021, Fangzhi Zuo <Jerry.Zuo at amd.com> wrote:
> +/* DSC Extended Capability Branch Total DSC Resources */
> +#define DP_DSC_SUPPORT_AND_DSC_DECODER_COUNT		0x2260	/* 2.0 */
> +# define DP_DSC_DECODER_COUNT_MASK			(0b111 << 5)
> +# define DP_DSC_DECODER_COUNT_SHIFT			5
> +#define DP_DSC_MAX_SLICE_COUNT_AND_AGGREGATION_0	0x2270	/* 2.0 */
> +# define DP_DSC_DECODER_0_MAXIMUM_SLICE_COUNT_MASK	(1 << 0)
> +# define DP_DSC_DECODER_0_AGGREGATION_SUPPORT_MASK	(0b111 << 1)
> +# define DP_DSC_DECODER_0_AGGREGATION_SUPPORT_SHIFT	1

The patch was merged a while back, but only now I noticed the use of
binary constants, which in C is a GCC and Clang extension [1][2]. There
are some instances in the kernel, but not a whole lot.

Do we want to avoid or embrace them going forward? Or meh?


BR,
Jani.


[1] https://gcc.gnu.org/onlinedocs/gcc/Binary-constants.html
[2] https://clang.llvm.org/docs/LanguageExtensions.html#c-14-binary-literals

-- 
Jani Nikula, Intel Open Source Graphics Center


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