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Re: [PATCH 1/2] regulator: core: Use a bitfield for continuous_voltage_range

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On Thu, 2016-01-21 at 20:24 +0000, Mark Brown wrote:
> Using a bitfield enables the compiler to lay out the structure more
> efficiently when we have other boolean flags since multiple values can
> be included in a single byte.
> 
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
>  include/linux/regulator/driver.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
> index 16ac9e108806..3ac0f306f033 100644
> --- a/include/linux/regulator/driver.h
> +++ b/include/linux/regulator/driver.h
> @@ -281,7 +281,7 @@ struct regulator_desc {
>  			    const struct regulator_desc *,
>  			    struct regulator_config *);
>  	int id;
> -	bool continuous_voltage_range;
> +	unsigned int continuous_voltage_range:1;

Is this really valuable?

There are already padding bytes that are unused
and adding a couple more bools would be space
cost-free and more readable.

I believe that read/write of bytes is also more
efficient on some architectures than bit field
read/modify/write uses.

>  	unsigned n_voltages;
>  	const struct regulator_ops *ops;
>  	int irq;

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[PATCH 1/2] regulator: core: Use a bitfield for continuous_voltage_range Mark Brown <broonie@kernel.org> - 2016-01-21 21:30 +0100
  [PATCH 2/2] regulator: core: Provide per-regulator runtime PM support Mark Brown <broonie@kernel.org> - 2016-01-21 21:30 +0100
    Re: [PATCH 2/2] regulator: core: Provide per-regulator runtime PM  support kbuild test robot <lkp@intel.com> - 2016-01-21 23:00 +0100
  Re: [PATCH 1/2] regulator: core: Use a bitfield for  continuous_voltage_range Joe Perches <joe@perches.com> - 2016-01-22 20:20 +0100
    Re: [PATCH 1/2] regulator: core: Use a bitfield for  continuous_voltage_range Mark Brown <broonie@kernel.org> - 2016-01-22 22:40 +0100
      Re: [PATCH 1/2] regulator: core: Use a bitfield for  continuous_voltage_range Joe Perches <joe@perches.com> - 2016-01-22 22:50 +0100
        Re: [PATCH 1/2] regulator: core: Use a bitfield for  continuous_voltage_range Mark Brown <broonie@kernel.org> - 2016-01-23 16:20 +0100

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