linux-kernel - Re: [PATCH] regmap: speed up the regcache

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Message-ID: <56679D42.3030708@cmss.chinamobile.com>
Date:	Wed, 09 Dec 2015 11:17:22 +0800
From:	Xiubo Li <lixiubo@...s.chinamobile.com>
To:	Mark Brown <broonie@...nel.org>
CC:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] regmap: speed up the regcache_init()



On 09/12/2015 01:05, Mark Brown wrote:
> On Thu, Dec 03, 2015 at 10:19:10AM +0800, Xiubo Li wrote:
>
>> If the cache is not used by the device driver, there is not need to
>> check the striding of the registers. It will just return 0 from
>> regcache_init() and let the register striding be checked in proper
>> place when needed.
>> -	for (i = 0; i < config->num_reg_defaults; i++)
>> -		if (config->reg_defaults[i].reg % map->reg_stride)
>> -			return -EINVAL;
>> -
>>   	if (map->cache_type == REGCACHE_NONE) {
>>   		map->cache_bypass = true;
>>   		return 0;
>>   	}
> If we're not using the register cache why are there defaults in the
> first place?
Yes, usually when the register cache is not used, the number of the
defaults should be zero, but for some drivers like drv2267.c/led_lp8860.c
will add the defaults register values though the cache type is
REGCACHE_NONE for some reasons.

This patch may be not the best, but will be a bit meaningful for some
drivers like drv2267.c/led_lp8860.c for now.

Thanks,

BRs

Xiubo








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