This patch reads charge delay from tsc DT node and writes to REG_CHARGEDELAY register. If the charge delay is not specified in DT then default value of 0x400(CHARGEDLY_OPENDLY) is used. Signed-off-by: Vignesh R <vigneshr@xxxxxx> --- v6: - Move Documentation from DT patch to driver code. v5: - print out a warning when ti,charge-delay is not specified v4: - Set charge delay to 0x400 as default. Most devices function normally at this value .../devicetree/bindings/input/touchscreen/ti-tsc-adc.txt | 15 +++++++++++++++ drivers/input/touchscreen/ti_am335x_tsc.c | 14 +++++++++++++- 2 files changed, 28 insertions(+), 1 deletion(-) diff --git a/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt index 878549ba814d..6c4fb34823d3 100644 --- a/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt +++ b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt @@ -28,6 +28,20 @@ Required properties: ti,adc-channels: List of analog inputs available for ADC. AIN0 = 0, AIN1 = 1 and so on till AIN7 = 7. +Optional properties: +- child "tsc" + ti,charge-delay: Length of touch screen charge delay step in terms of + ADC clock cycles. Charge delay value should be large + in order to avoid false pen-up events. This value + effects the overall sampling speed, hence need to be + kept as low as possible, while avoiding false pen-up + event. Start from a lower value, say 0x400, and + increase value until false pen-up events are avoided. + The pen-up detection happens immediately after the + charge step, so this does in fact function as a + hardware knob for adjusting the amount of "settling + time". + Example: tscadc: tscadc@44e0d000 { compatible = "ti,am3359-tscadc"; @@ -36,6 +50,7 @@ Example: ti,x-plate-resistance = <200>; ti,coordiante-readouts = <5>; ti,wire-config = <0x00 0x11 0x22 0x33>; + ti,charge-delay = <0x400>; }; adc { diff --git a/drivers/input/touchscreen/ti_am335x_tsc.c b/drivers/input/touchscreen/ti_am335x_tsc.c index 0625c102a1d0..7c0f6b21559d 100644 --- a/drivers/input/touchscreen/ti_am335x_tsc.c +++ b/drivers/input/touchscreen/ti_am335x_tsc.c @@ -52,6 +52,7 @@ struct titsc { u32 bit_xp, bit_xn, bit_yp, bit_yn; u32 inp_xp, inp_xn, inp_yp, inp_yn; u32 step_mask; + u32 charge_delay; }; static unsigned int titsc_readl(struct titsc *ts, unsigned int reg) @@ -177,7 +178,7 @@ static void titsc_step_config(struct titsc *ts_dev) config = titsc_readl(ts_dev, REG_IDLECONFIG); titsc_writel(ts_dev, REG_CHARGECONFIG, config); - titsc_writel(ts_dev, REG_CHARGEDELAY, CHARGEDLY_OPENDLY); + titsc_writel(ts_dev, REG_CHARGEDELAY, ts_dev->charge_delay); /* coordinate_readouts + 1 ... coordinate_readouts + 2 is for Z */ config = STEPCONFIG_MODE_HWSYNC | @@ -368,6 +369,17 @@ static int titsc_parse_dt(struct platform_device *pdev, if (err < 0) return err; + err = of_property_read_u32(node, "ti,charge-delay", + &ts_dev->charge_delay); + /* + * If ti,charge-delay value is not specified, then use + * CHARGEDLY_OPENDLY as the default value. + */ + if (err < 0) { + ts_dev->charge_delay = CHARGEDLY_OPENDLY; + dev_warn(&pdev->dev, "ti,charge-delay not specified\n"); + } + return of_property_read_u32_array(node, "ti,wire-config", ts_dev->config_inp, ARRAY_SIZE(ts_dev->config_inp)); } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html