linux-kernel - Re: [RFC V3] regmap: change bool to 1 bit variable in struct regmap

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Message-ID: <20151012104858.GA6786@pengutronix.de>
Date:	Mon, 12 Oct 2015 12:48:58 +0200
From:	Markus Pargmann <mpa@...gutronix.de>
To:	yalin wang <yalin.wang2010@...il.com>
Cc:	broonie@...nel.org, gregkh@...uxfoundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC V3] regmap: change bool to 1 bit variable in struct regmap

Hi,

On Fri, Oct 09, 2015 at 03:51:22PM +0800, yalin wang wrote:
> This patch change some bool variables in struct regmap {  }
> to be u8 v : 1 type, so that we can shrink the sizeof of struct regmap.
> 
> Signed-off-by: yalin wang <yalin.wang2010@...il.com>
> ---
>  drivers/base/regmap/internal.h | 39 +++++++++++++++++++--------------------
>  1 file changed, 19 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
> index 3df9770..dac341c 100644
> --- a/drivers/base/regmap/internal.h
> +++ b/drivers/base/regmap/internal.h
> @@ -68,7 +68,6 @@ struct regmap {
>  	void *bus_context;
>  	const char *name;
>  
> -	bool async;
>  	spinlock_t async_lock;
>  	wait_queue_head_t async_waitq;
>  	struct list_head async_list;
> @@ -102,8 +101,26 @@ struct regmap {
>  	int (*reg_update_bits)(void *context, unsigned int reg,
>  			       unsigned int mask, unsigned int val);
>  
> -	bool defer_caching;
> +	u8 async:1;
> +	u8 defer_caching:1;
> +	/* if set, remember to free reg_defaults_raw */
> +	u8 cache_free:1;
> +	/* if set, the HW registers are known to match map->reg_defaults */
> +	u8 no_sync_defaults:1;
>  
> +	/* if set, converts bulk read to single read */
> +	u8 use_single_read:1;
> +	/* if set, converts bulk read to single read */
> +	u8 use_single_write:1;
> +	/* if set, the device supports multi write mode */
> +	u8 can_multi_write:1;
> +
> +	/* if set, only the cache is modified not the HW */
> +	bool cache_only;
> +	/* if set, only the HW is modified not the cache */
> +	bool cache_bypass;
> +	/* if set, the cache contains newer data than the HW */
> +	bool cache_dirty;

Why are these last three variables just moved and not changed to u8 of
size 1?

Regards,

Markus

>  	u8 read_flag_mask;
>  	u8 write_flag_mask;
>  
> @@ -124,31 +141,13 @@ struct regmap {
>  	/* number of entries in reg_defaults_raw */
>  	unsigned int num_reg_defaults_raw;
>  
> -	/* if set, only the cache is modified not the HW */
> -	bool cache_only;
> -	/* if set, only the HW is modified not the cache */
> -	bool cache_bypass;
> -	/* if set, remember to free reg_defaults_raw */
> -	bool cache_free;
> -
>  	struct reg_default *reg_defaults;
>  	const void *reg_defaults_raw;
>  	void *cache;
> -	/* if set, the cache contains newer data than the HW */
> -	bool cache_dirty;
> -	/* if set, the HW registers are known to match map->reg_defaults */
> -	bool no_sync_defaults;
>  
>  	struct reg_sequence *patch;
>  	int patch_regs;
>  
> -	/* if set, converts bulk read to single read */
> -	bool use_single_read;
> -	/* if set, converts bulk read to single read */
> -	bool use_single_write;
> -	/* if set, the device supports multi write mode */
> -	bool can_multi_write;
> -
>  	/* if set, raw reads/writes are limited to this size */
>  	size_t max_raw_read;
>  	size_t max_raw_write;
> -- 
> 1.9.1
> 
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