linux-kernel - Re: [PATCH] drivers: iio: pressure: Fixes BMP38x and BMP390 SPI support

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Message-ID: <20240220175536.00007440@Huawei.com>
Date: Tue, 20 Feb 2024 17:55:36 +0000
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Vasileios Amoiridis <vassilisamir@...il.com>
CC: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, <jic23@...nel.org>,
	<lars@...afoo.de>, <ang.iglesiasg@...il.com>, <linus.walleij@...aro.org>,
	<semen.protsenko@...aro.org>, <linux-iio@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drivers: iio: pressure: Fixes BMP38x and BMP390 SPI
 support

On Tue, 20 Feb 2024 18:46:24 +0100
Vasileios Amoiridis <vassilisamir@...il.com> wrote:

> On Tue, Feb 20, 2024 at 04:09:26PM +0200, Andy Shevchenko wrote:
> > On Mon, Feb 19, 2024 at 08:13:59PM +0100, Vasileios Amoiridis wrote:  
> > > According to the datasheet of BMP38x and BMP390 devices, for an SPI
> > > read operation the first byte that is returned needs to be dropped,
> > > and the rest of the bytes are the actual data returned from the
> > > sensor.  
> > 
> > ...
> >   
> > >  #include <linux/spi/spi.h>
> > >  #include <linux/err.h>
> > >  #include <linux/regmap.h>
> > > +#include <linux/bits.h>  
> > 
> > I see that it's unsorted, but try to squeeze a new header to the better place
> > where more will be kept sorted. With given context, it should go before all
> > others, but it might be even better location.
> > 
> > ...
> >   
> 
> So you would suggest a re-ordering of the headers with a reverse
> christmas-tree? I don't see it used in the other drivers of the IIO
> subsystem but I can do it as well
Separate patch + alphabetical but in blocks.

linux/*
then
linux/iio/*
then
asm/*

First 2 can be combined though if you prefer that. Any asm definitely separate.

> 
> > > +static int bmp380_regmap_spi_read(void *context, const void *reg,
> > > +				  size_t reg_size, void *val, size_t val_size)
> > > +{
> > > +	struct spi_device *spi = to_spi_device(context);
> > > +	u8 rx_buf[4];
> > > +	ssize_t status;
> > > +
> > > +	/*
> > > +	 * Maximum number of consecutive bytes read for a temperature or
> > > +	 * pressure measurement is 3.
> > > +	 */
> > > +	if (val_size > 3)
> > > +		return -EINVAL;
> > > +	/*
> > > +	 * According to the BMP3xx datasheets, for a basic SPI read opertion,
> > > +	 * the first byte needs to be dropped and the rest are the requested
> > > +	 * data.
> > > +	 */
> > > +	status = spi_write_then_read(spi, reg, 1, rx_buf, val_size + 1);
> > > +	if (status)
> > > +		return status;  
> >   
> > > +	memcpy(val, rx_buf + 1, val_size);  
> > 
> > Okay, endianess is defined in the regmap_bus below...
> >   
> > > +	return 0;
> > > +}  
> > 
> > -- 
> > With Best Regards,
> > Andy Shevchenko
> > 
> >   
>