linux-kernel - Re: [PATCH v6 3/5] i2c: add support for HiSilicon I2C controller

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Message-ID: <f1d50200-93f5-2c35-933a-01a1e7622983@linux.intel.com>
Date:   Wed, 7 Apr 2021 11:32:10 +0300
From:   Jarkko Nikula <jarkko.nikula@...ux.intel.com>
To:     Yicong Yang <yangyicong@...ilicon.com>, wsa@...nel.org,
        andriy.shevchenko@...ux.intel.com, linux-i2c@...r.kernel.org,
        Sergey.Semin@...kalelectronics.ru, linux-kernel@...r.kernel.org
Cc:     digetx@...il.com, treding@...dia.com, rmk+kernel@...linux.org.uk,
        song.bao.hua@...ilicon.com, john.garry@...wei.com,
        mika.westerberg@...ux.intel.com, prime.zeng@...wei.com,
        linuxarm@...wei.com
Subject: Re: [PATCH v6 3/5] i2c: add support for HiSilicon I2C controller

Hi

On 3/31/21 4:36 PM, Yicong Yang wrote:
> +	ret = device_property_read_u64(dev, "clk_rate", &ctlr->clk_rate_khz);
> +	if (ret) {
> +		dev_err(dev, "failed to get clock frequency, ret = %d\n", ret);
> +		return ret;
> +	}
> +
> +	ctlr->clk_rate_khz = DIV_ROUND_UP_ULL(ctlr->clk_rate_khz, HZ_PER_KHZ);
> +

I'd use a temp variable here for reading the "clk_rate" property in 
Hertz and calculating the derived kHz value from it. As a bonus allow to 
use u32 for clk_rate_khz instead of u64. u32 will still provide plenty 
of headroom :-)

Reason for temp variable is for me it's confusing to see statement like 
"rate_khz = rate_khz / 1000".

Jarkko