Message-ID: <53B3E5AA.9060300@rock-chips.com>
Date: Wed, 02 Jul 2014 18:57:46 +0800
From: Jianqun <xjq@rock-chips.com>
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To: Huang Tao <huangtao@rock-chips.com>, Mark Brown <broonie@kernel.org>
CC: 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> <53B359FD.3080809@rock-chips.com>
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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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Rockchip Electronics Co.Ltd
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