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Commit bf223612 authored by Vignesh R's avatar Vignesh R Committed by Dmitry Torokhov
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Input: ti_am335x_tsc - read charge delay from DT 



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: default avatarVignesh R <vigneshr@ti.com>
Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
parent 344d635b

Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt

+15 −0
Original line number Diff line number Diff line
@@ -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 {

drivers/input/touchscreen/ti_am335x_tsc.c

+13 −1
Original line number Diff line number Diff line
@@ -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));

}