Re: [PATCH] nvme: hwmon: provide temperature min and max values for each sensor

From: Christoph Hellwig <hch@lst.de>
To: Akinobu Mita <akinobu.mita@gmail.com>
Cc: linux-nvme@lists.infradead.org, linux-hwmon@vger.kernel.org,
	Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@fb.com>,
	Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
	Jean Delvare <jdelvare@suse.com>,
	Guenter Roeck <linux@roeck-us.net>
Subject: Re: [PATCH] nvme: hwmon: provide temperature min and max values for each sensor
Date: Mon, 11 Nov 2019 17:53:06 +0100	[thread overview]
Message-ID: <20191111165306.GA19814@lst.de> (raw)
In-Reply-To: <1573395466-19526-1-git-send-email-akinobu.mita@gmail.com>

On Sun, Nov 10, 2019 at 11:17:46PM +0900, Akinobu Mita wrote:
> +static int nvme_get_temp_thresh(struct nvme_ctrl *ctrl, int sensor, bool under,
> +				long *temp)
> +{
> +	unsigned int threshold = sensor << NVME_TEMP_THRESH_SELECT_SHIFT;
> +	int status;
> +	int ret;
> +
> +	if (under)
> +		threshold |= NVME_TEMP_THRESH_TYPE_UNDER;
> +
> +	ret = nvme_get_features(ctrl, NVME_FEAT_TEMP_THRESH, threshold, NULL, 0,
> +				&status);
> +	if (!ret)
> +		*temp = ((status & NVME_TEMP_THRESH_MASK) - 273) * 1000;
> +
> +	return ret <= 0 ? ret : -EIO;

This looks a little obsfucated.  aI'd prefer something like:

	if (ret > 0)
		return -EIO;
	if (ret < 0)
		return ret;
	*temp = ((status & NVME_TEMP_THRESH_MASK) - 273) * 1000;
	return 0;

> +	return ret <= 0 ? ret : -EIO;

Similarly here, something like:

	if (ret > 0)
		return -EIO;
	return ret;

> +		err = nvme_get_temp_thresh(data->ctrl, channel, false, val);
> +		if (err)
> +			*val = (data->ctrl->wctemp - 273) * 1000;

Can we have a helper for this (x - 273) * 1000 conversion?  It is
repeated quite a bit over the code in this file.