Re: [PATCH 2/3] iio: chemical: add support for Sensirion SPS30 sensor

From: Jonathan Cameron <jic23@jic23.retrosnub.co.uk>
To: Tomasz Duszynski <tduszyns@gmail.com>
Cc: Himanshu Jha <himanshujha199640@gmail.com>,
	linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org,
	devicetree@vger.kernel.org
Subject: Re: [PATCH 2/3] iio: chemical: add support for Sensirion SPS30 sensor
Date: Sat, 1 Dec 2018 16:02:03 +0000	[thread overview]
Message-ID: <20181201160203.0b26e393@archlinux> (raw)
In-Reply-To: <20181126204803.GA19277@arch>

On Mon, 26 Nov 2018 21:48:07 +0100
Tomasz Duszynski <tduszyns@gmail.com> wrote:

> On Sun, Nov 25, 2018 at 04:14:34PM +0530, Himanshu Jha wrote:
> > On Sat, Nov 24, 2018 at 11:14:14PM +0100, Tomasz Duszynski wrote:  
> > > Add support for Sensirion SPS30 particulate matter sensor.
> > >
> > > Signed-off-by: Tomasz Duszynski <tduszyns@gmail.com>
> > > ---
> > >  drivers/iio/chemical/Kconfig  |  11 ++
> > >  drivers/iio/chemical/Makefile |   1 +
> > >  drivers/iio/chemical/sps30.c  | 359 ++++++++++++++++++++++++++++++++++
> > >  3 files changed, 371 insertions(+)
> > >  create mode 100644 drivers/iio/chemical/sps30.c  
> >
> > []
> >  
> > > +#define pr_fmt(fmt) "sps30: " fmt  
> >
> > I don't see its usage ?
> >  
> 
> Hint: checkout how dev_err() is defined.
> 
> > > +#include <linux/crc8.h>
> > > +#include <linux/delay.h>
> > > +#include <linux/i2c.h>
> > > +#include <linux/iio/buffer.h>
> > > +#include <linux/iio/iio.h>
> > > +#include <linux/iio/sysfs.h>
> > > +#include <linux/iio/trigger_consumer.h>
> > > +#include <linux/iio/triggered_buffer.h>
> > > +#include <linux/module.h>
> > > +
> > > +#define SPS30_CRC8_POLYNOMIAL 0x31
> > > +
> > > +/* SPS30 commands */
> > > +#define SPS30_START_MEAS 0x0010
> > > +#define SPS30_STOP_MEAS 0x0104
> > > +#define SPS30_RESET 0xd304
> > > +#define SPS30_READ_DATA_READY_FLAG 0x0202
> > > +#define SPS30_READ_DATA 0x0300
> > > +#define SPS30_READ_SERIAL 0xD033  
> >
> > Could you please put a tab and align these macros.
> >
> >   #define SPS30_START_MEAS		0x0010
> >   #define SPS30_STOP_MEAS		0x0104
> >  
> 
> In my opinion this sort of alignment does not pay off in the long run.
> Adding a new definition, a slightly longer one perhaps, can easily break
> formatting.
> 
> So I would stay with current one.

Personally I agree with you on this one.  I don't care enough to
say either way though normally!

> 
> >  
> > > +static int sps30_write_then_read(struct sps30_state *state, u8 *buf,
> > > +				 int buf_size, u8 *data, int data_size)
> > > +{
> > > +	/* every two received data bytes are checksummed */
> > > +	u8 tmp[data_size + data_size / 2];  
> >
> > No VLAs!
> >
> > https://lore.kernel.org/lkml/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com/
> >  
> 
> Looks like -Wvla is some fairly recent addition to KBUILD_CFLAGS.

Yeah, that was only after a 'lot' of effort over years to get the number
present down to a small number.

I wrote plenty of them in the early days of IIO so got a lot of
those patches as part of the move to introducing the warning :)

Jonathan

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