On 07/22/13 15:03, Hector Palacios wrote:
> The LRADC virtual channels have an 18 bit field to store the sum of up
> to 2^5 accumulated samples. The read_raw function however only operates
> over a single sample (12 bit resolution).
> In order to use this field for scaling operations, we need it to be the
> exact resolution value of the LRADC.
> Besides, the driver was using an 18 bit mask (LRADC_CH_VALUE_MASK) to
> report touch coordinates to userland. A 12 bit mask should be used instead
> or else the touch libraries will expect a coordinates range between 0
> and 0x3ffff (18 bits), instead of between 0 and 0xfff (12 bits).
>
> Signed-off-by: Hector Palacios <hector.palacios@xxxxxxxx>
> Acked-by: Marek Vasut <marex@xxxxxxx>
> Acked-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
Applied to the togreg branch of iio.git
Thanks,
Jonathan
> ---
> drivers/staging/iio/adc/mxs-lradc.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/staging/iio/adc/mxs-lradc.c b/drivers/staging/iio/adc/mxs-lradc.c
> index 9f52a28..56667da 100644
> --- a/drivers/staging/iio/adc/mxs-lradc.c
> +++ b/drivers/staging/iio/adc/mxs-lradc.c
> @@ -225,6 +225,9 @@ struct mxs_lradc {
> #define LRADC_CTRL4_LRADCSELECT_MASK(n) (0xf << ((n) * 4))
> #define LRADC_CTRL4_LRADCSELECT_OFFSET(n) ((n) * 4)
>
> +#define LRADC_RESOLUTION 12
> +#define LRADC_SINGLE_SAMPLE_MASK ((1 << LRADC_RESOLUTION) - 1)
> +
> /*
> * Raw I/O operations
> */
> @@ -540,9 +543,10 @@ static int mxs_lradc_ts_register(struct mxs_lradc *lradc)
> __set_bit(EV_ABS, input->evbit);
> __set_bit(EV_KEY, input->evbit);
> __set_bit(BTN_TOUCH, input->keybit);
> - input_set_abs_params(input, ABS_X, 0, LRADC_CH_VALUE_MASK, 0, 0);
> - input_set_abs_params(input, ABS_Y, 0, LRADC_CH_VALUE_MASK, 0, 0);
> - input_set_abs_params(input, ABS_PRESSURE, 0, LRADC_CH_VALUE_MASK, 0, 0);
> + input_set_abs_params(input, ABS_X, 0, LRADC_SINGLE_SAMPLE_MASK, 0, 0);
> + input_set_abs_params(input, ABS_Y, 0, LRADC_SINGLE_SAMPLE_MASK, 0, 0);
> + input_set_abs_params(input, ABS_PRESSURE, 0, LRADC_SINGLE_SAMPLE_MASK,
> + 0, 0);
>
> lradc->ts_input = input;
> input_set_drvdata(input, lradc);
> @@ -817,7 +821,7 @@ static const struct iio_buffer_setup_ops mxs_lradc_buffer_ops = {
> .channel = (idx), \
> .scan_type = { \
> .sign = 'u', \
> - .realbits = 18, \
> + .realbits = LRADC_RESOLUTION, \
> .storagebits = 32, \
> }, \
> }
>
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