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

From: Huang Tao <huangtao@rock-chips.com>
To: Mark Brown <broonie@kernel.org>
Cc: yzq@rock-chips.com, devicetree@vger.kernel.org,
	alsa-devel@alsa-project.org, heiko@sntech.de, tiwai@suse.de,
	linux-kernel@vger.kernel.org, zhangqing@rock-chips.com,
	lgirdwood@gmail.com, robh+dt@kernel.org,
	kever.yang@rock-chips.com, zyw@rock-chips.com,
	jianqun <xjq@rock-chips.com>,
	kfx@rock-chips.com, grant.likely@linaro.org, cf@rock-chips.com,
	hj@rock-chips.com, zhenfu.fang@rock-chips.com
Subject: Re: [PATCH 2/2] ASoC: add driver for Rockchip RK3xxx I2S controller
Date: Wed, 02 Jul 2014 09:01:49 +0800	[thread overview]
Message-ID: <53B359FD.3080809@rock-chips.com> (raw)
In-Reply-To: <20140701170747.GA15028@sirena.org.uk>

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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