linux-kernel - Re: [PATCH 4/9] staging: iio: tsl2583: remove redundant power off sequence in taos_chip

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Message-ID: <f16b351d-917b-6cc4-e8a2-881967bfb581@kernel.org>
Date:   Sun, 6 Nov 2016 11:51:50 +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 4/9] staging: iio: tsl2583: remove redundant power off
 sequence in taos_chip_on()

On 03/11/16 12:56, Brian Masney wrote:
> taos_chip_on() explicitly turns the sensor power on and then writes the
> 8 registers that are stored in taos_config. The first register in
> taos_config is the CONTROL register and the configuration is set to
> turn the power off. The existing state sequence in taos_chip_on() is:
> 
> - Turn device power on
> - Turn device power off (via taos_config)
> - Configure other 7 registers (via taos_config)
> - Turn device power on, enable ADC
> 
> This patch changes the code so that the device is not powered off via
> taos_config.
> 
> 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>
Seems sensible.

Applied to the togreg branch of iio.git.

Thanks,

Jonathan
> ---
>  drivers/staging/iio/light/tsl2583.c | 13 ++-----------
>  1 file changed, 2 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/staging/iio/light/tsl2583.c b/drivers/staging/iio/light/tsl2583.c
> index 709f446..7fb09c6 100644
> --- a/drivers/staging/iio/light/tsl2583.c
> +++ b/drivers/staging/iio/light/tsl2583.c
> @@ -410,17 +410,8 @@ static int taos_chip_on(struct iio_dev *indio_dev)
>  	chip->als_saturation = als_count * 922; /* 90% of full scale */
>  	chip->als_time_scale = (als_time + 25) / 50;
>  
> -	/*
> -	 * TSL258x Specific power-on / adc enable sequence
> -	 * Power on the device 1st.
> -	 */
> -	utmp = TSL258X_CNTL_PWR_ON;
> -	ret = i2c_smbus_write_byte_data(chip->client,
> -					TSL258X_CMD_REG | TSL258X_CNTRL, utmp);
> -	if (ret < 0) {
> -		dev_err(&chip->client->dev, "taos_chip_on failed on CNTRL reg.\n");
> -		return ret;
> -	}
> +	/* Power on the device; ADC off. */
> +	chip->taos_config[TSL258X_CNTRL] = TSL258X_CNTL_PWR_ON;
>  
>  	/*
>  	 * Use the following shadow copy for our delay before enabling ADC.
>