linux-kernel - Re: [PATCH 2/2] ASoC: add driver for Rockchip RK3xxx I2S controller

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Date:	Wed, 02 Jul 2014 18:57:46 +0800
From:	Jianqun <xjq@...k-chips.com>
To:	Huang Tao <huangtao@...k-chips.com>,
	Mark Brown <broonie@...nel.org>
CC:	heiko@...ech.de, lgirdwood@...il.com, perex@...ex.cz,
	tiwai@...e.de, grant.likely@...aro.org, robh+dt@...nel.org,
	linux-kernel@...r.kernel.org, alsa-devel@...a-project.org,
	devicetree@...r.kernel.org, zhangqing@...k-chips.com,
	hj@...k-chips.com, kever.yang@...k-chips.com, zyw@...k-chips.com,
	yzq@...k-chips.com, zhenfu.fang@...k-chips.com, cf@...k-chips.com,
	kfx@...k-chips.com
Subject: Re: [PATCH 2/2] ASoC: add driver for Rockchip RK3xxx I2S controller

Hi Mark:

Since regmap_update_bits is int style, I have to error check every time after call it.
Also I find that the tegra_i2s.c call the function without error checking,

Could you tell me the right way to handle the regmap_update_bits ?


Best Regards

On 2014年07月02日 09:01, Huang Tao wrote:
> Hi, Mark:
> 
> 于 2014年07月02日 01:07, Mark Brown 写道:
>>> +static inline void i2s_writel(struct rk_i2s_dev *i2s, u32 value,
>>>> +			      unsigned int offset)
>>>> +{
>>>> +	writel_relaxed(value, i2s->regs + offset);
>>>> +}
>>>> +
>>>> +static inline u32 i2s_readl(struct rk_i2s_dev *i2s, unsigned int offset)
>>>> +{
>>>> +	return readl_relaxed(i2s->regs + offset);
>>>> +}
>> Perhaps use regmap?  The main advantage would be the debug
>> infrastructure, though you could also use _update_bits() to reduce the
>> amount of time spent locked.
>>
> Are you sure? This is a I2S driver, we can write the register directly,
> do not through I2C or SPI bus.
> Write a register is only a few instructions on ARM, but write through
> regmap, it may take a long path.
> I think it will just consume CPU power and make the whole thing more
> complex.
> Could you tell me what benefits we can get if use regmap? Or something I
> just missing?
> 
> 
> 

-- 
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许 剑 群 Jay
Rockchip Electronics Co.Ltd
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