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Subject: Re: [PATCH v6 3/5] i2c: add support for HiSilicon I2C controller
To:     Yicong Yang <yangyicong@hisilicon.com>, wsa@kernel.org,
        andriy.shevchenko@linux.intel.com, linux-i2c@vger.kernel.org,
        Sergey.Semin@baikalelectronics.ru, linux-kernel@vger.kernel.org
Cc:     digetx@gmail.com, treding@nvidia.com, rmk+kernel@armlinux.org.uk,
        song.bao.hua@hisilicon.com, john.garry@huawei.com,
        mika.westerberg@linux.intel.com, prime.zeng@huawei.com,
        linuxarm@huawei.com
References: <1617197790-30627-1-git-send-email-yangyicong@hisilicon.com>
 <1617197790-30627-4-git-send-email-yangyicong@hisilicon.com>
From:   Jarkko Nikula <jarkko.nikula@linux.intel.com>
Message-ID: <f1d50200-93f5-2c35-933a-01a1e7622983@linux.intel.com>
Date:   Wed, 7 Apr 2021 11:32:10 +0300
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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