All of lore.kernel.org
 help / color / mirror / Atom feed
From: Jonathan Cameron <jic23@kernel.org>
To: "Stefan Brüns" <stefan.bruens@rwth-aachen.de>
Cc: <linux-iio@vger.kernel.org>, Rob Herring <robh@kernel.org>,
	Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
	<linux-kernel@vger.kernel.org>,
	Manivannan Sadhasivam <manivannanece23@gmail.com>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Hartmut Knaack <knaack.h@gmx.de>
Subject: Re: [PATCH v3 3/4] iio: light: vl6180: Cleanup als_gain lookup, avoid register readback
Date: Sat, 30 Sep 2017 21:29:39 +0100	[thread overview]
Message-ID: <20170930212939.02383bd2@archlinux> (raw)
In-Reply-To: <d65aa875-6922-4cb4-800c-caed28067099@rwthex-w2-a.rwth-ad.de>

On Sun, 24 Sep 2017 23:59:19 +0200
Stefan Brüns <stefan.bruens@rwth-aachen.de> wrote:

> Instead of manually iterating the array of allowed gain values, use
> find_closest. Storing the current gain setting avoids accessing the
> hardware on each query.
> 
> Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
> 

Applied to the togreg branch of iio.git and pushed out as testing
for the autobuilders to play with it.

Thanks,

Jonathan

> ---
> 
> Changes in v3: None
> Changes in v2:
> - Add missing spaces
> 
>  drivers/iio/light/vl6180.c | 85 ++++++++++++++++++++++++----------------------
>  1 file changed, 44 insertions(+), 41 deletions(-)
> 
> diff --git a/drivers/iio/light/vl6180.c b/drivers/iio/light/vl6180.c
> index 9b056c83a90a..49e9f92cd116 100644
> --- a/drivers/iio/light/vl6180.c
> +++ b/drivers/iio/light/vl6180.c
> @@ -24,6 +24,7 @@
>  #include <linux/err.h>
>  #include <linux/of.h>
>  #include <linux/delay.h>
> +#include <linux/util_macros.h>
>  
>  #include <linux/iio/iio.h>
>  #include <linux/iio/sysfs.h>
> @@ -86,6 +87,7 @@
>  struct vl6180_data {
>  	struct i2c_client *client;
>  	struct mutex lock;
> +	unsigned int als_gain_milli;
>  	unsigned int als_it_ms;
>  };
>  
> @@ -276,19 +278,17 @@ static const struct iio_chan_spec vl6180_channels[] = {
>  };
>  
>  /*
> - * Columns 3 & 4 represent the same value in decimal and hex notations.
> - * Kept in order to avoid the datatype conversion while reading the
> - * hardware_gain.
> + * Available Ambient Light Sensor gain settings, 1/1000th, and
> + * corresponding setting for the VL6180_ALS_GAIN register
>   */
> -static const int vl6180_als_gain[8][4] = {
> -	{ 1,	0,	70,	VL6180_ALS_GAIN_1 },
> -	{ 1,    250000, 69,	VL6180_ALS_GAIN_1_25 },
> -	{ 1,    670000, 68,	VL6180_ALS_GAIN_1_67 },
> -	{ 2,    500000, 67,	VL6180_ALS_GAIN_2_5 },
> -	{ 5,    0,      66,	VL6180_ALS_GAIN_5 },
> -	{ 10,   0,      65,	VL6180_ALS_GAIN_10 },
> -	{ 20,   0,      64,	VL6180_ALS_GAIN_20 },
> -	{ 40,   0,      71,	VL6180_ALS_GAIN_40 }
> +static const int vl6180_als_gain_tab[8] = {
> +	1000, 1250, 1670, 2500, 5000, 10000, 20000, 40000
> +};
> +static const u8 vl6180_als_gain_tab_bits[8] = {
> +	VL6180_ALS_GAIN_1,    VL6180_ALS_GAIN_1_25,
> +	VL6180_ALS_GAIN_1_67, VL6180_ALS_GAIN_2_5,
> +	VL6180_ALS_GAIN_5,    VL6180_ALS_GAIN_10,
> +	VL6180_ALS_GAIN_20,   VL6180_ALS_GAIN_40
>  };
>  
>  static int vl6180_read_raw(struct iio_dev *indio_dev,
> @@ -296,7 +296,7 @@ static int vl6180_read_raw(struct iio_dev *indio_dev,
>  				int *val, int *val2, long mask)
>  {
>  	struct vl6180_data *data = iio_priv(indio_dev);
> -	int ret, i;
> +	int ret;
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
> @@ -328,17 +328,11 @@ static int vl6180_read_raw(struct iio_dev *indio_dev,
>  
>  		return IIO_VAL_INT_PLUS_MICRO;
>  	case IIO_CHAN_INFO_HARDWAREGAIN:
> -		ret = vl6180_read_byte(data->client, VL6180_ALS_GAIN);
> -		if (ret < 0)
> -			return -EINVAL;
> -		for (i = 0; i < ARRAY_SIZE(vl6180_als_gain); i++) {
> -			if (ret == vl6180_als_gain[i][2]) {
> -				*val = vl6180_als_gain[i][0];
> -				*val2 = vl6180_als_gain[i][1];
> -			}
> -		}
> +		*val = data->als_gain_milli;
> +		*val2 = 1000;
> +
> +		return IIO_VAL_FRACTIONAL;
>  
> -		return IIO_VAL_INT_PLUS_MICRO;
>  	default:
>  		return -EINVAL;
>  	}
> @@ -364,25 +358,33 @@ static int vl6180_hold(struct vl6180_data *data, bool hold)
>  
>  static int vl6180_set_als_gain(struct vl6180_data *data, int val, int val2)
>  {
> -	int i, ret;
> -
> -	for (i = 0; i < ARRAY_SIZE(vl6180_als_gain); i++) {
> -		if (val == vl6180_als_gain[i][0] &&
> -			val2 == vl6180_als_gain[i][1]) {
> -			mutex_lock(&data->lock);
> -			ret = vl6180_hold(data, true);
> -			if (ret < 0)
> -				goto fail;
> -			ret = vl6180_write_byte(data->client, VL6180_ALS_GAIN,
> -				vl6180_als_gain[i][3]);
> -fail:
> -			vl6180_hold(data, false);
> -			mutex_unlock(&data->lock);
> -			return ret;
> -		}
> -	}
> +	int i, ret, gain;
> +
> +	if (val < 1 || val > 40)
> +		return -EINVAL;
>  
> -	return -EINVAL;
> +	gain = (val * 1000000 + val2) / 1000;
> +	if (gain < 1 || gain > 40000)
> +		return -EINVAL;
> +
> +	i = find_closest(gain, vl6180_als_gain_tab,
> +			 ARRAY_SIZE(vl6180_als_gain_tab));
> +
> +	mutex_lock(&data->lock);
> +	ret = vl6180_hold(data, true);
> +	if (ret < 0)
> +		goto fail;
> +
> +	ret = vl6180_write_byte(data->client, VL6180_ALS_GAIN,
> +				vl6180_als_gain_tab_bits[i]);
> +
> +	if (ret >= 0)
> +		data->als_gain_milli = vl6180_als_gain_tab[i];
> +
> +fail:
> +	vl6180_hold(data, false);
> +	mutex_unlock(&data->lock);
> +	return ret;
>  }
>  
>  static int vl6180_set_it(struct vl6180_data *data, int val, int val2)
> @@ -479,6 +481,7 @@ static int vl6180_init(struct vl6180_data *data)
>  		return ret;
>  
>  	/* ALS gain: 1 */
> +	data->als_gain_milli = 1000;
>  	ret = vl6180_write_byte(client, VL6180_ALS_GAIN, VL6180_ALS_GAIN_1);
>  	if (ret < 0)
>  		return ret;

  reply	other threads:[~2017-09-30 20:29 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20170924215920.7465-1-stefan.bruens@rwth-aachen.de>
2017-09-24 21:59 ` [PATCH v3 1/4] iio: light: vl6180: Move range check to integration time setter, cleanup Stefan Brüns
2017-09-30 20:21   ` Jonathan Cameron
2017-09-24 21:59 ` [PATCH v3 2/4] iio: light: vl6180: Avoid readback of integration time register Stefan Brüns
2017-09-30 20:23   ` Jonathan Cameron
2017-09-24 21:59 ` [PATCH v3 3/4] iio: light: vl6180: Cleanup als_gain lookup, avoid register readback Stefan Brüns
2017-09-30 20:29   ` Jonathan Cameron [this message]
2017-09-24 21:59 ` [PATCH v3 4/4] iio: light: vl6180: Correct ALS scale for non-default gain/integration time Stefan Brüns
2017-09-30 20:31   ` Jonathan Cameron

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20170930212939.02383bd2@archlinux \
    --to=jic23@kernel.org \
    --cc=knaack.h@gmx.de \
    --cc=lars@metafoo.de \
    --cc=linux-iio@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=manivannanece23@gmail.com \
    --cc=pmeerw@pmeerw.net \
    --cc=robh@kernel.org \
    --cc=stefan.bruens@rwth-aachen.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.