On 30/08/16 13:27, Nicolas Ferre wrote:
> On newer components compatible with the at91sam9x5, the Touchscreen
> Switches Closure Time or TSSCTIM value of the Touchscreen Mode Register is
> not filled at all.
> On some hardware, having no time indicated for it may lead to incoherent
> values and jitter.
> We fix this time to 10us as it is usually difficult to retrieve impedance
> values from LCD manufacturers.
>
> Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
Hi Nicolas,
Stable / fixes material or just have it head for the next merge window?
Jonathan
> ---
> drivers/iio/adc/at91_adc.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
> index 0438c68015e8..bbdac07f4aaa 100644
> --- a/drivers/iio/adc/at91_adc.c
> +++ b/drivers/iio/adc/at91_adc.c
> @@ -113,6 +113,7 @@
> #define AT91_ADC_TSMR_TSAV (3 << 4) /* Averages samples */
> #define AT91_ADC_TSMR_TSAV_(x) ((x) << 4)
> #define AT91_ADC_TSMR_SCTIM (0x0f << 16) /* Switch closure time */
> +#define AT91_ADC_TSMR_SCTIM_(x) ((x) << 16)
> #define AT91_ADC_TSMR_PENDBC (0x0f << 28) /* Pen Debounce time */
> #define AT91_ADC_TSMR_PENDBC_(x) ((x) << 28)
> #define AT91_ADC_TSMR_NOTSDMA (1 << 22) /* No Touchscreen DMA */
> @@ -150,6 +151,7 @@
> #define MAX_RLPOS_BITS 10
> #define TOUCH_SAMPLE_PERIOD_US_RL 10000 /* 10ms, the SoC can't keep up with 2ms */
> #define TOUCH_SHTIM 0xa
> +#define TOUCH_SCTIM_US 10 /* 10us for the Touchscreen Switches Closure Time */
>
> /**
> * struct at91_adc_reg_desc - Various informations relative to registers
> @@ -1001,7 +1003,9 @@ static void atmel_ts_close(struct input_dev *dev)
>
> static int at91_ts_hw_init(struct at91_adc_state *st, u32 adc_clk_khz)
> {
> + struct iio_dev *idev = iio_priv_to_dev(st);
> u32 reg = 0;
> + u32 tssctim = 0;
> int i = 0;
>
> /* a Pen Detect Debounce Time is necessary for the ADC Touch to avoid
> @@ -1034,11 +1038,20 @@ static int at91_ts_hw_init(struct at91_adc_state *st, u32 adc_clk_khz)
> return 0;
> }
>
> + /* Touchscreen Switches Closure time needed for allowing the value to
> + * stabilize.
> + * Switch Closure Time = (TSSCTIM * 4) ADCClock periods
> + */
> + tssctim = DIV_ROUND_UP(TOUCH_SCTIM_US * adc_clk_khz / 1000, 4);
> + dev_dbg(&idev->dev, "adc_clk at: %d KHz, tssctim at: %d\n",
> + adc_clk_khz, tssctim);
> +
> if (st->touchscreen_type == ATMEL_ADC_TOUCHSCREEN_4WIRE)
> reg = AT91_ADC_TSMR_TSMODE_4WIRE_PRESS;
> else
> reg = AT91_ADC_TSMR_TSMODE_5WIRE;
>
> + reg |= AT91_ADC_TSMR_SCTIM_(tssctim) & AT91_ADC_TSMR_SCTIM;
> reg |= AT91_ADC_TSMR_TSAV_(st->caps->ts_filter_average)
> & AT91_ADC_TSMR_TSAV;
> reg |= AT91_ADC_TSMR_PENDBC_(st->ts_pendbc) & AT91_ADC_TSMR_PENDBC;
>
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