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Date:   Mon, 29 Oct 2018 02:24:07 +0530
From:   Nishad Kamdar <nishadkamdar@gmail.com>
To:     Jonathan Cameron <jic23@kernel.org>
Cc:     Slawomir Stepien <sst@poczta.fm>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Michael Hennerich <Michael.Hennerich@analog.com>,
        Hartmut Knaack <knaack.h@gmx.de>,
        Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-iio@vger.kernel.org, devel@driverdev.osuosl.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 3/3] staging: iio: ad2s1210: Add device tree support.
Message-ID: <20181028205406.GA31715@nishad>
References: <cover.1540712249.git.nishadkamdar@gmail.com>
 <473e6abfe959e1ac78fe65bf8dc53ad25ad3b358.1540712249.git.nishadkamdar@gmail.com>
 <20181028145108.1079227f@archlinux>
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On Sun, Oct 28, 2018 at 02:51:08PM +0000, Jonathan Cameron wrote:
> On Sun, 28 Oct 2018 13:23:23 +0530
> Nishad Kamdar <nishadkamdar@gmail.com> wrote:
> 
> > Replace platform data with device tree support.
> > 
> > Signed-off-by: Nishad Kamdar <nishadkamdar@gmail.com>
> The whole gpio in or out thing makes less and less sense to
> me and seems to contradict the datasheet.
> 
> If I'm not missing something I would just get rid of the option.
> If I am missing something (not hard in the datasheet which, whilst
> fairly clear, is a rather long ;)
> 
> Jonathan
> 

Ok, I'll drop it.
> > ---
> >  drivers/staging/iio/resolver/Kconfig    |  1 +
> >  drivers/staging/iio/resolver/ad2s1210.c | 17 ++++++++---------
> >  drivers/staging/iio/resolver/ad2s1210.h | 17 -----------------
> >  3 files changed, 9 insertions(+), 26 deletions(-)
> > 
> > diff --git a/drivers/staging/iio/resolver/Kconfig b/drivers/staging/iio/resolver/Kconfig
> > index 6a469ee6101f..cc1202ff813d 100644
> > --- a/drivers/staging/iio/resolver/Kconfig
> > +++ b/drivers/staging/iio/resolver/Kconfig
> > @@ -15,6 +15,7 @@ config AD2S90
> >  
> >  config AD2S1210
> >  	tristate "Analog Devices ad2s1210 driver"
> > +	depends on OF
> >  	depends on SPI
> >  	depends on GPIOLIB || COMPILE_TEST
> >  	help
> > diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c
> > index 0234869e9d74..5ecdb5785132 100644
> > --- a/drivers/staging/iio/resolver/ad2s1210.c
> > +++ b/drivers/staging/iio/resolver/ad2s1210.c
> > @@ -17,6 +17,7 @@
> >  #include <linux/delay.h>
> >  #include <linux/gpio/consumer.h>
> >  #include <linux/module.h>
> > +#include <linux/of.h>
> >  
> >  #include <linux/iio/iio.h>
> >  #include <linux/iio/sysfs.h>
> > @@ -76,7 +77,6 @@ struct ad2s1210_gpio {
> >  };
> >  
> >  struct ad2s1210_state {
> > -	const struct ad2s1210_platform_data *pdata;
> >  	struct mutex lock;
> >  	struct spi_device *sdev;
> >  	struct gpio_desc *sample;
> > @@ -84,6 +84,7 @@ struct ad2s1210_state {
> >  	struct gpio_desc *a1;
> >  	struct gpio_desc *res0;
> >  	struct gpio_desc *res1;
> > +	bool gpioin;
> >  	unsigned int fclkin;
> >  	unsigned int fexcit;
> >  	bool hysteresis;
> > @@ -314,7 +315,7 @@ static ssize_t ad2s1210_store_control(struct device *dev,
> >  	}
> >  	st->resolution
> >  		= ad2s1210_resolution_value[data & AD2S1210_SET_RESOLUTION];
> > -	if (st->pdata->gpioin) {
> > +	if (st->gpioin) {
> >  		data = ad2s1210_read_resolution_pin(st);
> >  		if (data != st->resolution)
> >  			dev_warn(dev, "ad2s1210: resolution settings not match\n");
> > @@ -376,7 +377,7 @@ static ssize_t ad2s1210_store_resolution(struct device *dev,
> >  	}
> >  	st->resolution
> >  		= ad2s1210_resolution_value[data & AD2S1210_SET_RESOLUTION];
> > -	if (st->pdata->gpioin) {
> > +	if (st->gpioin) {
> >  		data = ad2s1210_read_resolution_pin(st);
> >  		if (data != st->resolution)
> >  			dev_warn(dev, "ad2s1210: resolution settings not match\n");
> > @@ -603,7 +604,7 @@ static int ad2s1210_initial(struct ad2s1210_state *st)
> >  	int ret;
> >  
> >  	mutex_lock(&st->lock);
> > -	if (st->pdata->gpioin)
> > +	if (st->gpioin)
> >  		st->resolution = ad2s1210_read_resolution_pin(st);
> >  	else
> >  		ad2s1210_set_resolution_pin(st);
> > @@ -644,7 +645,7 @@ static int ad2s1210_setup_gpios(struct ad2s1210_state *st)
> >  	int ret, i;
> >  	struct spi_device *spi = st->sdev;
> >  	struct ad2s1210_gpio *pin;
> > -	unsigned long flags = st->pdata->gpioin ? GPIOD_IN : GPIOD_OUT_LOW;
> > +	unsigned long flags = st->gpioin ? GPIOD_IN : GPIOD_OUT_LOW;
> >  
> >  	struct ad2s1210_gpio gpios[] = {
> >  		{ .ptr = &st->sample, .name = "sample", .flags = GPIOD_IN },
> > @@ -673,16 +674,14 @@ static int ad2s1210_probe(struct spi_device *spi)
> >  {
> >  	struct iio_dev *indio_dev;
> >  	struct ad2s1210_state *st;
> > +	struct device_node *np = spi->dev.of_node;
> >  	int ret;
> >  
> > -	if (!spi->dev.platform_data)
> > -		return -EINVAL;
> > -
> >  	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> >  	if (!indio_dev)
> >  		return -ENOMEM;
> >  	st = iio_priv(indio_dev);
> > -	st->pdata = spi->dev.platform_data;
> > +	st->gpioin = of_property_read_bool(np, "gpioin");
> 
> Hmm. This bothered me in the earlier patch.  How are we meant to configure
> these pins... (and this time I actually loaded the datasheet)
> 
> A0 and A1 always seem to be control signals written to the device so
> I don't really understand why we would ever want them to be 'inputs'
> on our host.
> 
> RES0 and RES1 are also control signals. Clearly marked as logic inputs.
> 
> The only thing I can think here is there is an evaluation board out there
> were we are not in control of these, some other controller is.
> That is a pretty weird board if so, hence I would only support the version
> where we use GPIO outputs from the host.
> 
> This will further simplify patch 1 and get rid fo the need for this
> non standard bit of devicetree binding.
> 
> 
> >  	ret = ad2s1210_setup_gpios(st);
> >  	if (ret < 0)
> >  		return ret;
> > diff --git a/drivers/staging/iio/resolver/ad2s1210.h b/drivers/staging/iio/resolver/ad2s1210.h
> > index 63d479b20a6c..e69de29bb2d1 100644
> > --- a/drivers/staging/iio/resolver/ad2s1210.h
> > +++ b/drivers/staging/iio/resolver/ad2s1210.h
> > @@ -1,17 +0,0 @@
> > -/*
> > - * ad2s1210.h plaform data for the ADI Resolver to Digital Converters:
> > - * AD2S1210
> > - *
> > - * Copyright (c) 2010-2010 Analog Devices Inc.
> > - *
> > - * This program is free software; you can redistribute it and/or modify
> > - * it under the terms of the GNU General Public License version 2 as
> > - * published by the Free Software Foundation.
> > - */
> > -#ifndef _AD2S1210_H
> > -#define _AD2S1210_H
> > -
> > -struct ad2s1210_platform_data {
> > -	bool			gpioin;
> > -};
> > -#endif /* _AD2S1210_H */
> 

Ok, I'll make the changes.

Thanks for the review.

regards,
Nishad