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Date:   Wed, 24 Oct 2018 00:33:15 +0530
From:   Nishad Kamdar <nishadkamdar@gmail.com>
To:     Slawomir Stepien <sst@poczta.fm>
Cc:     Lars-Peter Clausen <lars@metafoo.de>,
        Michael Hennerich <Michael.Hennerich@analog.com>,
        Jonathan Cameron <jic23@kernel.org>,
        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 v2] staging: iio: ad2s1210: Switch to the gpio descriptor
 interface
Message-ID: <20181023190312.GA12915@nishad>
References: <20181022163935.GA756@nishad>
 <20181023111356.GA318@x220.localdomain>
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On Tue, Oct 23, 2018 at 01:13:56PM +0200, Slawomir Stepien wrote:
> On paź 22, 2018 22:09, Nishad Kamdar wrote:
> > Use the gpiod interface instead of the deprecated old non-descriptor
> > interface.
> 
> Hi
> 
> > Signed-off-by: Nishad Kamdar <nishadkamdar@gmail.com>
> > ---
> > Changes in v2:
> >  - Use the spi_device struct embedded in st instead
> >    of passing it as an argument to ad2s1210_setup_gpios().
> >  - Use an array of structs to reduce redundant code in
> >    in ad2s1210_setup_gpios().
> >  - Remove ad2s1210_free_gpios() as devm API is being used.
> 
> Some few more comments on that changes below.
> 
> > ---
> >  drivers/staging/iio/resolver/ad2s1210.c | 91 +++++++++++++------------
> >  drivers/staging/iio/resolver/ad2s1210.h |  3 -
> >  2 files changed, 48 insertions(+), 46 deletions(-)
> > 
> > diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c
> > index ac13b99bd9cb..e4c222b47574 100644
> > --- a/drivers/staging/iio/resolver/ad2s1210.c
> > +++ b/drivers/staging/iio/resolver/ad2s1210.c
> > @@ -15,7 +15,7 @@
> >  #include <linux/slab.h>
> >  #include <linux/sysfs.h>
> >  #include <linux/delay.h>
> > -#include <linux/gpio.h>
> > +#include <linux/gpio/consumer.h>
> >  #include <linux/module.h>
> >  
> >  #include <linux/iio/iio.h>
> > @@ -69,10 +69,21 @@ enum ad2s1210_mode {
> >  
> >  static const unsigned int ad2s1210_resolution_value[] = { 10, 12, 14, 16 };
> >  
> > +struct ad2s1210_gpio {
> > +	struct gpio_desc *ptr;
> 
> You are going to use this ptr to change a pointer it points to. So it must be a
> pointer to pointer: **ptr;
> 
> > +	char *name;
> 
> I guess it should be const char *.
> 
> > +	unsigned long flags;
> > +};
> > +
> >  struct ad2s1210_state {
> >  	const struct ad2s1210_platform_data *pdata;
> >  	struct mutex lock;
> >  	struct spi_device *sdev;
> > +	struct gpio_desc *sample;
> > +	struct gpio_desc *a0;
> > +	struct gpio_desc *a1;
> > +	struct gpio_desc *res0;
> > +	struct gpio_desc *res1;
> >  	unsigned int fclkin;
> >  	unsigned int fexcit;
> >  	bool hysteresis;
> > @@ -91,8 +102,8 @@ static const int ad2s1210_mode_vals[4][2] = {
> >  static inline void ad2s1210_set_mode(enum ad2s1210_mode mode,
> >  				     struct ad2s1210_state *st)
> >  {
> > -	gpio_set_value(st->pdata->a[0], ad2s1210_mode_vals[mode][0]);
> > -	gpio_set_value(st->pdata->a[1], ad2s1210_mode_vals[mode][1]);
> > +	gpiod_set_value(st->a0, ad2s1210_mode_vals[mode][0]);
> > +	gpiod_set_value(st->a1, ad2s1210_mode_vals[mode][1]);
> >  	st->mode = mode;
> >  }
> >  
> > @@ -152,8 +163,8 @@ int ad2s1210_update_frequency_control_word(struct ad2s1210_state *st)
> >  
> >  static unsigned char ad2s1210_read_resolution_pin(struct ad2s1210_state *st)
> >  {
> > -	int resolution = (gpio_get_value(st->pdata->res[0]) << 1) |
> > -			  gpio_get_value(st->pdata->res[1]);
> > +	int resolution = (gpiod_get_value(st->res0) << 1) |
> > +			  gpiod_get_value(st->res1);
> >  
> >  	return ad2s1210_resolution_value[resolution];
> >  }
> > @@ -164,10 +175,10 @@ static const int ad2s1210_res_pins[4][2] = {
> >  
> >  static inline void ad2s1210_set_resolution_pin(struct ad2s1210_state *st)
> >  {
> > -	gpio_set_value(st->pdata->res[0],
> > -		       ad2s1210_res_pins[(st->resolution - 10) / 2][0]);
> > -	gpio_set_value(st->pdata->res[1],
> > -		       ad2s1210_res_pins[(st->resolution - 10) / 2][1]);
> > +	gpiod_set_value(st->res0,
> > +			ad2s1210_res_pins[(st->resolution - 10) / 2][0]);
> > +	gpiod_set_value(st->res1,
> > +			ad2s1210_res_pins[(st->resolution - 10) / 2][1]);
> >  }
> >  
> >  static inline int ad2s1210_soft_reset(struct ad2s1210_state *st)
> > @@ -401,15 +412,15 @@ static ssize_t ad2s1210_clear_fault(struct device *dev,
> >  	int ret;
> >  
> >  	mutex_lock(&st->lock);
> > -	gpio_set_value(st->pdata->sample, 0);
> > +	gpiod_set_value(st->sample, 0);
> >  	/* delay (2 * tck + 20) nano seconds */
> >  	udelay(1);
> > -	gpio_set_value(st->pdata->sample, 1);
> > +	gpiod_set_value(st->sample, 1);
> >  	ret = ad2s1210_config_read(st, AD2S1210_REG_FAULT);
> >  	if (ret < 0)
> >  		goto error_ret;
> > -	gpio_set_value(st->pdata->sample, 0);
> > -	gpio_set_value(st->pdata->sample, 1);
> > +	gpiod_set_value(st->sample, 0);
> > +	gpiod_set_value(st->sample, 1);
> >  error_ret:
> >  	mutex_unlock(&st->lock);
> >  
> > @@ -466,7 +477,7 @@ static int ad2s1210_read_raw(struct iio_dev *indio_dev,
> >  	s16 vel;
> >  
> >  	mutex_lock(&st->lock);
> > -	gpio_set_value(st->pdata->sample, 0);
> > +	gpiod_set_value(st->sample, 0);
> >  	/* delay (6 * tck + 20) nano seconds */
> >  	udelay(1);
> >  
> > @@ -512,7 +523,7 @@ static int ad2s1210_read_raw(struct iio_dev *indio_dev,
> >  	}
> >  
> >  error_ret:
> > -	gpio_set_value(st->pdata->sample, 1);
> > +	gpiod_set_value(st->sample, 1);
> >  	/* delay (2 * tck + 20) nano seconds */
> >  	udelay(1);
> >  	mutex_unlock(&st->lock);
> > @@ -630,30 +641,30 @@ static const struct iio_info ad2s1210_info = {
> >  
> >  static int ad2s1210_setup_gpios(struct ad2s1210_state *st)
> >  {
> > -	unsigned long flags = st->pdata->gpioin ? GPIOF_DIR_IN : GPIOF_DIR_OUT;
> > -	struct gpio ad2s1210_gpios[] = {
> > -		{ st->pdata->sample, GPIOF_DIR_IN, "sample" },
> > -		{ st->pdata->a[0], flags, "a0" },
> > -		{ st->pdata->a[1], flags, "a1" },
> > -		{ st->pdata->res[0], flags, "res0" },
> > -		{ st->pdata->res[0], flags, "res1" },
> > +	int ret = 0, i = 0;
> 
> You do not need to init that i with 0.
> Also the ret do not have to be 0. If you return just 0 at the on this function.
> 
> > +	struct spi_device *spi = st->sdev;
> > +	unsigned long flags = st->pdata->gpioin ? GPIOD_IN : GPIOD_OUT_LOW;
> > +
> > +	struct ad2s1210_gpio gpios[] = {
> > +		{st->sample, "sample", GPIOD_IN},
> > +		{st->a0, "a0", flags},
> > +		{st->a1, "a1", flags},
> > +		{st->res0, "res0", flags},
> > +		{st->res1, "res1", flags},
> 
> To change a pointer, you need to pass an address of that pointer.
> I think you should you . notation when initializing the struct.
> 
> >  	};
> >  
> > -	return gpio_request_array(ad2s1210_gpios, ARRAY_SIZE(ad2s1210_gpios));
> > -}
> > -
> > -static void ad2s1210_free_gpios(struct ad2s1210_state *st)
> > -{
> > -	unsigned long flags = st->pdata->gpioin ? GPIOF_DIR_IN : GPIOF_DIR_OUT;
> > -	struct gpio ad2s1210_gpios[] = {
> > -		{ st->pdata->sample, GPIOF_DIR_IN, "sample" },
> > -		{ st->pdata->a[0], flags, "a0" },
> > -		{ st->pdata->a[1], flags, "a1" },
> > -		{ st->pdata->res[0], flags, "res0" },
> > -		{ st->pdata->res[0], flags, "res1" },
> > -	};
> > +	for (i = 0; i < ARRAY_SIZE(gpios); i++) {
> 
> I do not know if that is a common practise, but you can set a pointer to gpio[i]
> as the first instruction in this for, so you would not have to write this whole
> gpio[i]:
> 
> pin = &gpios[i]
> 
> and then: pin->ptr, etc.
> 
> > +		gpios[i].ptr = devm_gpiod_get(&spi->dev, gpios[i].name,
> > +					      gpios[i].flags);
> > +		if (IS_ERR(gpios[i].ptr)) {
> > +			ret = PTR_ERR(gpios[i].ptr);
> > +			dev_err(&spi->dev, "Failed to request %s GPIO: %d\n",
> > +				gpios[i].name, ret);
> > +			return ret;
> > +		}
> > +	}
> >  
> > -	gpio_free_array(ad2s1210_gpios, ARRAY_SIZE(ad2s1210_gpios));
> > +	return ret;
> >  }
> >  
> >  static int ad2s1210_probe(struct spi_device *spi)
> > @@ -692,18 +703,13 @@ static int ad2s1210_probe(struct spi_device *spi)
> >  
> >  	ret = iio_device_register(indio_dev);
> >  	if (ret)
> > -		goto error_free_gpios;
> > -
> 
> Removing a empty line here, that is here to make it more readable.
> 
> > +		return ret;
> >  	st->fclkin = spi->max_speed_hz;
> >  	spi->mode = SPI_MODE_3;
> >  	spi_setup(spi);
> >  	ad2s1210_initial(st);
> >  
> >  	return 0;
> > -
> > -error_free_gpios:
> > -	ad2s1210_free_gpios(st);
> > -	return ret;
> >  }
> >  
> >  static int ad2s1210_remove(struct spi_device *spi)
> > @@ -711,7 +717,6 @@ static int ad2s1210_remove(struct spi_device *spi)
> >  	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> >  
> >  	iio_device_unregister(indio_dev);
> > -	ad2s1210_free_gpios(iio_priv(indio_dev));
> >  
> >  	return 0;
> >  }
> > diff --git a/drivers/staging/iio/resolver/ad2s1210.h b/drivers/staging/iio/resolver/ad2s1210.h
> > index e9b2147701fc..63d479b20a6c 100644
> > --- a/drivers/staging/iio/resolver/ad2s1210.h
> > +++ b/drivers/staging/iio/resolver/ad2s1210.h
> > @@ -12,9 +12,6 @@
> >  #define _AD2S1210_H
> >  
> >  struct ad2s1210_platform_data {
> > -	unsigned int		sample;
> > -	unsigned int		a[2];
> > -	unsigned int		res[2];
> >  	bool			gpioin;
> >  };
> >  #endif /* _AD2S1210_H */
> 
> -- 
> Slawomir Stepien
Hello,

Ok, I'll make the changes.

Thanks for the review.

regards,
Nishad