Message-ID: <53B359FD.3080809@rock-chips.com>
Date: Wed, 02 Jul 2014 09:01:49 +0800
From: Huang Tao <huangtao@rock-chips.com>
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To: Mark Brown <broonie@kernel.org>
CC: jianqun <xjq@rock-chips.com>, heiko@sntech.de, lgirdwood@gmail.com,
        perex@perex.cz, tiwai@suse.de, grant.likely@linaro.org,
        robh+dt@kernel.org, linux-kernel@vger.kernel.org,
        alsa-devel@alsa-project.org, devicetree@vger.kernel.org,
        zhangqing@rock-chips.com, hj@rock-chips.com, kever.yang@rock-chips.com,
        zyw@rock-chips.com, yzq@rock-chips.com, zhenfu.fang@rock-chips.com,
        cf@rock-chips.com, kfx@rock-chips.com
Subject: Re: [PATCH 2/2] ASoC: add driver for Rockchip RK3xxx I2S controller
References: <1404203860-30712-1-git-send-email-xjq@rock-chips.com> <1404204458-30881-1-git-send-email-xjq@rock-chips.com> <20140701170747.GA15028@sirena.org.uk>
In-Reply-To: <20140701170747.GA15028@sirena.org.uk>
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Sender: linux-kernel-owner@vger.kernel.org

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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