linux-kernel - Re: [PATCH 2/9] staging: iio: tsl2583: removed unused code from device probing

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Message-ID: <1ebfaec1-fe18-5692-9fae-b4161c118c4c@kernel.org>
Date:   Sun, 6 Nov 2016 11:46:50 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Brian Masney <masneyb@...tation.org>, linux-iio@...r.kernel.org
Cc:     devel@...verdev.osuosl.org, gregkh@...uxfoundation.org,
        lars@...afoo.de, pmeerw@...erw.net, knaack.h@....de,
        linux-kernel@...r.kernel.org, Jon.Brenner@....com
Subject: Re: [PATCH 2/9] staging: iio: tsl2583: removed unused code from
 device probing

On 03/11/16 12:56, Brian Masney wrote:
> taos_probe() queries the all of the sensor's registers and loads all of
> the values into a buffer stored on the stack. Only the chip ID register
> was actually used. Change the probe function to just query the chip ID
> register on the device.
> 
> Verified that the driver still functions correctly using a TSL2581
> hooked up to a Raspberry Pi 2.
> 
> Signed-off-by: Brian Masney <masneyb@...tation.org>
Huh. I'm embarrassed that I didn't notice this bit of silliness in the
original reviews :)

Applied to the togreg branch of iio.git

Thanks,

Jonathan
> ---
>  drivers/staging/iio/light/tsl2583.c | 37 +++++++++++++------------------------
>  1 file changed, 13 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/staging/iio/light/tsl2583.c b/drivers/staging/iio/light/tsl2583.c
> index a3a9095..388440b 100644
> --- a/drivers/staging/iio/light/tsl2583.c
> +++ b/drivers/staging/iio/light/tsl2583.c
> @@ -31,8 +31,6 @@
>  #include <linux/iio/iio.h>
>  #include <linux/iio/sysfs.h>
>  
> -#define TSL258X_MAX_DEVICE_REGS		32
> -
>  /* Triton register offsets */
>  #define	TSL258X_REG_MAX		8
>  
> @@ -66,6 +64,9 @@
>  /* Lux calculation constants */
>  #define	TSL258X_LUX_CALC_OVER_FLOW		65535
>  
> +#define TSL2583_CHIP_ID			0x90
> +#define TSL2583_CHIP_ID_MASK		0xf0
> +
>  enum {
>  	TSL258X_CHIP_UNKNOWN = 0,
>  	TSL258X_CHIP_WORKING = 1,
> @@ -607,12 +608,6 @@ static const struct attribute_group tsl2583_attribute_group = {
>  	.attrs = sysfs_attrs_ctrl,
>  };
>  
> -/* Use the default register values to identify the Taos device */
> -static int taos_tsl258x_device(unsigned char *bufp)
> -{
> -	return ((bufp[TSL258X_CHIPID] & 0xf0) == 0x90);
> -}
> -
>  static const struct iio_chan_spec tsl2583_channels[] = {
>  	{
>  		.type = IIO_LIGHT,
> @@ -777,8 +772,7 @@ static const struct iio_info tsl2583_info = {
>  static int taos_probe(struct i2c_client *clientp,
>  		      const struct i2c_device_id *idp)
>  {
> -	int i, ret;
> -	unsigned char buf[TSL258X_MAX_DEVICE_REGS];
> +	int ret;
>  	struct tsl2583_chip *chip;
>  	struct iio_dev *indio_dev;
>  
> @@ -799,22 +793,17 @@ static int taos_probe(struct i2c_client *clientp,
>  	chip->taos_chip_status = TSL258X_CHIP_UNKNOWN;
>  	memcpy(chip->taos_config, taos_config, sizeof(chip->taos_config));
>  
> -	for (i = 0; i < TSL258X_MAX_DEVICE_REGS; i++) {
> -		ret = i2c_smbus_read_byte_data(clientp,
> -					       (TSL258X_CMD_REG |
> -						(TSL258X_CNTRL + i)));
> -		if (ret < 0) {
> -			dev_err(&clientp->dev,
> -				"i2c_smbus_read_byte from reg failed in taos_probe(), err = %d\n",
> -				ret);
> -			return ret;
> -		}
> -		buf[i] = ret;
> +	ret = i2c_smbus_read_byte_data(clientp,
> +				       TSL258X_CMD_REG | TSL258X_CHIPID);
> +	if (ret < 0) {
> +		dev_err(&clientp->dev,
> +			"%s failed to read the chip ID register\n", __func__);
> +		return ret;
>  	}
>  
> -	if (!taos_tsl258x_device(buf)) {
> -		dev_info(&clientp->dev,
> -			 "i2c device found but does not match expected id in taos_probe()\n");
> +	if ((ret & TSL2583_CHIP_ID_MASK) != TSL2583_CHIP_ID) {
> +		dev_info(&clientp->dev, "%s received an unknown chip ID %x\n",
> +			 __func__, ret);
>  		return -EINVAL;
>  	}
>  
>