On 11/25/13 12:42, Lars-Peter Clausen wrote:
> Some I2C controllers may not be able to handle transfer buffers that are placed
> on the stack.
>
> Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
Applied to the togreg branch of iio.git
> ---
> drivers/staging/iio/adc/ad7280a.c | 29 +++++++++++++++--------------
> 1 file changed, 15 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/staging/iio/adc/ad7280a.c b/drivers/staging/iio/adc/ad7280a.c
> index 89ee65b..1ac11f6 100644
> --- a/drivers/staging/iio/adc/ad7280a.c
> +++ b/drivers/staging/iio/adc/ad7280a.c
> @@ -134,6 +134,8 @@ struct ad7280_state {
> unsigned char aux_threshhigh;
> unsigned char aux_threshlow;
> unsigned char cb_mask[AD7280A_MAX_CHAIN];
> +
> + __be32 buf[2] ____cacheline_aligned;
> };
>
> static void ad7280_crc8_build_table(unsigned char *crc_tab)
> @@ -189,22 +191,22 @@ static void ad7280_delay(struct ad7280_state *st)
> msleep(1);
> }
>
> -static int __ad7280_read32(struct spi_device *spi, unsigned *val)
> +static int __ad7280_read32(struct ad7280_state *st, unsigned *val)
> {
> - __be32 rx_buf, tx_buf = cpu_to_be32(AD7280A_READ_TXVAL);
> int ret;
> -
> struct spi_transfer t = {
> - .tx_buf = &tx_buf,
> - .rx_buf = &rx_buf,
> + .tx_buf = &st->buf[0],
> + .rx_buf = &st->buf[1],
> .len = 4,
> };
>
> - ret = spi_sync_transfer(spi, &t, 1);
> + st->buf[0] = cpu_to_be32(AD7280A_READ_TXVAL);
> +
> + ret = spi_sync_transfer(st->spi, &t, 1);
> if (ret)
> return ret;
>
> - *val = be32_to_cpu(rx_buf);
> + *val = be32_to_cpu(st->buf[1]);
>
> return 0;
> }
> @@ -214,12 +216,11 @@ static int ad7280_write(struct ad7280_state *st, unsigned devaddr,
> {
> unsigned reg = (devaddr << 27 | addr << 21 |
> (val & 0xFF) << 13 | all << 12);
> - __be32 tx_buf;
>
> reg |= ad7280_calc_crc8(st->crc_tab, reg >> 11) << 3 | 0x2;
> - tx_buf = cpu_to_be32(reg);
> + st->buf[0] = cpu_to_be32(reg);
>
> - return spi_write(st->spi, &tx_buf, 4);
> + return spi_write(st->spi, &st->buf[0], 4);
> }
>
> static int ad7280_read(struct ad7280_state *st, unsigned devaddr,
> @@ -249,7 +250,7 @@ static int ad7280_read(struct ad7280_state *st, unsigned devaddr,
> if (ret)
> return ret;
>
> - __ad7280_read32(st->spi, &tmp);
> + __ad7280_read32(st, &tmp);
>
> if (ad7280_check_crc(st, tmp))
> return -EIO;
> @@ -287,7 +288,7 @@ static int ad7280_read_channel(struct ad7280_state *st, unsigned devaddr,
>
> ad7280_delay(st);
>
> - __ad7280_read32(st->spi, &tmp);
> + __ad7280_read32(st, &tmp);
>
> if (ad7280_check_crc(st, tmp))
> return -EIO;
> @@ -320,7 +321,7 @@ static int ad7280_read_all_channels(struct ad7280_state *st, unsigned cnt,
> ad7280_delay(st);
>
> for (i = 0; i < cnt; i++) {
> - __ad7280_read32(st->spi, &tmp);
> + __ad7280_read32(st, &tmp);
>
> if (ad7280_check_crc(st, tmp))
> return -EIO;
> @@ -363,7 +364,7 @@ static int ad7280_chain_setup(struct ad7280_state *st)
> return ret;
>
> for (n = 0; n <= AD7280A_MAX_CHAIN; n++) {
> - __ad7280_read32(st->spi, &val);
> + __ad7280_read32(st, &val);
> if (val == 0)
> return n - 1;
>
>
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