Adds a device tree parameter to set the open delay on the touchscreen
conversion steps. Increasing this parameter helps the touch accuracy on
some screens.
Signed-off-by: Michael Welling <mwell...@ieee.org>
---
.../bindings/input/touchscreen/ti-tsc-adc.txt | 5 +++++
drivers/input/touchscreen/ti_am335x_tsc.c | 18 ++++++++++++++----
2 files changed, 19 insertions(+), 4 deletions(-)
diff --git a/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
index b1163bf..cb11fda 100644
--- a/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
+++ b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
@@ -41,6 +41,11 @@ Optional properties:
charge step, so this does in fact function as a
hardware knob for adjusting the amount of "settling
time".
+ ti,open-delay: Open delay applied to all touchscreen conversion steps.
+ The value corresponds to the number of ADC clock
+ cycles to wait after applying the step configuration
+ registers and before sending the start of ADC
+ conversion. Maximum value is 0x3FFFF.
- child "adc"
ti,chan-step-opendelay: List of open delays for each channel of
diff --git a/drivers/input/touchscreen/ti_am335x_tsc.c
b/drivers/input/touchscreen/ti_am335x_tsc.c
index 191a1b8..37a9729 100644
--- a/drivers/input/touchscreen/ti_am335x_tsc.c
+++ b/drivers/input/touchscreen/ti_am335x_tsc.c
@@ -54,6 +54,7 @@ struct titsc {
u32 inp_xp, inp_xn, inp_yp, inp_yn;
u32 step_mask;
u32 charge_delay;
+ u32 open_delay;
};
static unsigned int titsc_readl(struct titsc *ts, unsigned int reg)
@@ -148,7 +149,7 @@ static void titsc_step_config(struct titsc *ts_dev)
end_step = first_step + tsc_steps;
for (i = end_step - ts_dev->coordinate_readouts; i < end_step; i++) {
titsc_writel(ts_dev, REG_STEPCONFIG(i), config);
- titsc_writel(ts_dev, REG_STEPDELAY(i), STEPCONFIG_OPENDLY);
+ titsc_writel(ts_dev, REG_STEPDELAY(i), ts_dev->open_delay);
}
config = 0;
@@ -172,7 +173,7 @@ static void titsc_step_config(struct titsc *ts_dev)
end_step = first_step + ts_dev->coordinate_readouts;
for (i = first_step; i < end_step; i++) {
titsc_writel(ts_dev, REG_STEPCONFIG(i), config);
- titsc_writel(ts_dev, REG_STEPDELAY(i), STEPCONFIG_OPENDLY);
+ titsc_writel(ts_dev, REG_STEPDELAY(i), ts_dev->open_delay);
}
/* Make CHARGECONFIG same as IDLECONFIG */
@@ -188,13 +189,13 @@ static void titsc_step_config(struct titsc *ts_dev)
STEPCONFIG_INP(ts_dev->inp_xp);
titsc_writel(ts_dev, REG_STEPCONFIG(end_step), config);
titsc_writel(ts_dev, REG_STEPDELAY(end_step),
- STEPCONFIG_OPENDLY);
+ ts_dev->open_delay);
end_step++;
config |= STEPCONFIG_INP(ts_dev->inp_yn);
titsc_writel(ts_dev, REG_STEPCONFIG(end_step), config);
titsc_writel(ts_dev, REG_STEPDELAY(end_step),
- STEPCONFIG_OPENDLY);
+ ts_dev->open_delay);
/* The steps end ... end - readouts * 2 + 2 and bit 0 for TS_Charge */
stepenable = 1;
@@ -392,6 +393,15 @@ static int titsc_parse_dt(struct platform_device *pdev,
dev_warn(&pdev->dev, "ti,charge-delay not specified\n");
}
+ err = of_property_read_u32(node, "ti,open-delay",
+ &ts_dev->open_delay);
+ /*
+ * If ti,open-delay value is not specified, then use
+ * STEPCONFIG_OPENDLY as the default value.
+ */
+ if (err < 0)
+ ts_dev->open_delay = STEPCONFIG_OPENDLY;
+
return of_property_read_u32_array(node, "ti,wire-config",
ts_dev->config_inp, ARRAY_SIZE(ts_dev->config_inp));
}
--
2.1.4
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