linux-kernel - Re: [PATCH v5 1/4] iio: chemical: scd30: add core driver

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Date:   Sat, 20 Jun 2020 17:25:02 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Tomasz Duszynski <tomasz.duszynski@...akon.com>
Cc:     <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <robh+dt@...nel.org>,
        <andy.shevchenko@...il.com>, <pmeerw@...erw.net>
Subject: Re: [PATCH v5 1/4] iio: chemical: scd30: add core driver

On Sun, 7 Jun 2020 19:58:09 +0200
Tomasz Duszynski <tomasz.duszynski@...akon.com> wrote:

> Add Sensirion SCD30 carbon dioxide core driver.
> 
> Signed-off-by: Tomasz Duszynski <tomasz.duszynski@...akon.com>

A few things I'd missed showed up in warnings when I applied this and
ran a sparse check.  Please fix up and send a v6.
Also sanity check the rest with sparse. Note if I'd missed this 0-day
would have sent use these warnings.

Thanks,

Jonathan

> +
> +static int scd30_read_meas(struct scd30_state *state)
> +{
> +	int i, ret;
> +
> +	ret = state->command(state, CMD_READ_MEAS, 0, state->meas, sizeof(state->meas));
> +	if (ret)
> +		return ret;
> +
> +	be32_to_cpu_array(state->meas, state->meas, ARRAY_SIZE(state->meas));

The type of the input to the above has the wrong endian markings.

CHECK   drivers/iio/chemical/scd30_core.c
drivers/iio/chemical/scd30_core.c:123:40: warning: incorrect type in argument 2 (different base types)
drivers/iio/chemical/scd30_core.c:123:40:    expected restricted __be32 const [usertype] *src
drivers/iio/chemical/scd30_core.c:123:40:    got int *

Whilst you could use a cast, it would be tidier to use an array of __be32.
 
> +
> +	for (i = 0; i < ARRAY_SIZE(state->meas); i++)
> +		state->meas[i] = scd30_float_to_fp(state->meas[i]);
> +
> +	/*
> +	 * co2 is left unprocessed while temperature and humidity are scaled
> +	 * to milli deg C and milli percent respectively.
> +	 */
> +	state->meas[SCD30_TEMP] *= 10;
> +	state->meas[SCD30_HR] *= 10;
> +
> +	return 0;
> +}
> +

...

> +
> +static irqreturn_t scd30_trigger_handler(int irq, void *p)
> +{
> +	struct iio_poll_func *pf = p;
> +	struct iio_dev *indio_dev = pf->indio_dev;
> +	struct scd30_state *state = iio_priv(indio_dev);
> +	struct {
> +		int data[SCD30_MEAS_COUNT];
> +		s64 ts __aligned(8);
> +	} scan = { 0, };
should be scan = { {0, }, }; or something like that
as first element happens to be an array.

Actually there is padding in here you need to zero I think.
So memset is a better bet.

> +	int ret;
> +
> +	mutex_lock(&state->lock);
> +	if (!iio_trigger_using_own(indio_dev))
> +		ret = scd30_read_poll(state);
> +	else
> +		ret = scd30_read_meas(state);
> +	memcpy(scan.data, state->meas, sizeof(state->meas));
> +	mutex_unlock(&state->lock);
> +	if (ret)
> +		goto out;
> +
> +	iio_push_to_buffers_with_timestamp(indio_dev, &scan, iio_get_time_ns(indio_dev));
> +out:
> +	iio_trigger_notify_done(indio_dev->trig);
> +	return IRQ_HANDLED;
> +}
> +
...