Re: [PATCH 1/6] IIO: GYRO: ADXRS450: Don't issue two messages, use two transfers

[Jonathan Cameron <jic23@cam.ac.uk>]

On 04/29/11 11:58, michael.hennerich@analog.com wrote:
> From: Michael Hennerich <michael.hennerich@analog.com>
> 
> Don't issue the same message twice, use two transfers and group them together
> 
> Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
> ---
>  drivers/staging/iio/gyro/adxrs450_core.c |   58 ++++++++++++++---------------
>  1 files changed, 28 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/staging/iio/gyro/adxrs450_core.c b/drivers/staging/iio/gyro/adxrs450_core.c
> index dcd88ff..a1a71b7 100644
> --- a/drivers/staging/iio/gyro/adxrs450_core.c
> +++ b/drivers/staging/iio/gyro/adxrs450_core.c
> @@ -40,29 +40,28 @@ static int adxrs450_spi_read_reg_16(struct device *dev,
>  	struct iio_dev *indio_dev = dev_get_drvdata(dev);
>  	struct adxrs450_state *st = iio_dev_get_devdata(indio_dev);
>  	int ret;
> -	struct spi_transfer xfers = {
> -		.tx_buf = st->tx,
> -		.rx_buf = st->rx,
> -		.bits_per_word = 8,
> -		.len = 4,
> +	struct spi_transfer xfers[] = {
> +		{
> +			.tx_buf = st->tx,
> +			.bits_per_word = 8,
> +			.len = 4,
> +			.cs_change = 1,
> +		}, {
> +			.rx_buf = st->rx,
> +			.bits_per_word = 8,
> +			.len = 4,
> +		},
>  	};
> -	/* Needs to send the command twice to get the wanted value */
> +
>  	mutex_lock(&st->buf_lock);
> -	st->tx[0] = ADXRS450_READ_DATA | reg_address >> 7;
> +	st->tx[0] = ADXRS450_READ_DATA | (reg_address >> 7);
>  	st->tx[1] = reg_address << 1;
>  	st->tx[2] = 0;
>  	st->tx[3] = 0;
> -	spi_message_init(&msg);
> -	spi_message_add_tail(&xfers, &msg);
> -	ret = spi_sync(st->us, &msg);
> -	if (ret) {
> -		dev_err(&st->us->dev, "problem while reading 16 bit register 0x%02x\n",
> -				reg_address);
> -		goto error_ret;
> -	}
> 
>  	spi_message_init(&msg);
> -	spi_message_add_tail(&xfers, &msg);
> +	spi_message_add_tail(&xfers[0], &msg);
> +	spi_message_add_tail(&xfers[1], &msg);
>  	ret = spi_sync(st->us, &msg);
>  	if (ret) {
>  		dev_err(&st->us->dev, "problem while reading 16 bit register 0x%02x\n",
> @@ -125,11 +124,17 @@ static int adxrs450_spi_sensor_data(struct device *dev, u16 *val)
>  	struct iio_dev *indio_dev = dev_get_drvdata(dev);
>  	struct adxrs450_state *st = iio_dev_get_devdata(indio_dev);
>  	int ret;
> -	struct spi_transfer xfers = {
> -		.tx_buf = st->tx,
> -		.rx_buf = st->rx,
> -		.bits_per_word = 8,
> -		.len = 4,
> +	struct spi_transfer xfers[] = {
> +		{
> +			.tx_buf = st->tx,
> +			.bits_per_word = 8,
> +			.len = 4,
> +			.cs_change = 1,
> +		}, {
> +			.rx_buf = st->rx,
> +			.bits_per_word = 8,
> +			.len = 4,
> +		},
>  	};
> 
>  	mutex_lock(&st->buf_lock);
> @@ -139,15 +144,8 @@ static int adxrs450_spi_sensor_data(struct device *dev, u16 *val)
>  	st->tx[3] = 0;
> 
>  	spi_message_init(&msg);
> -	spi_message_add_tail(&xfers, &msg);
> -	ret = spi_sync(st->us, &msg);
> -	if (ret) {
> -		dev_err(&st->us->dev, "Problem while reading sensor data\n");
> -		goto error_ret;
> -	}
> -
> -	spi_message_init(&msg);
> -	spi_message_add_tail(&xfers, &msg);
> +	spi_message_add_tail(&xfers[0], &msg);
> +	spi_message_add_tail(&xfers[1], &msg);
>  	ret = spi_sync(st->us, &msg);
>  	if (ret) {
>  		dev_err(&st->us->dev, "Problem while reading sensor data\n");
> --
> 1.6.0.2
> 
> 
>