[3/4] arm: boot: dts: am335x-evm: Make charge delay a DT parameter for tsc
diff mbox

Message ID 1414408111-2631-4-git-send-email-vigneshr@ti.com
State New, archived
Headers show

Commit Message

Vignesh Raghavendra Oct. 27, 2014, 11:08 a.m. UTC
The charge delay value is by default 0xB000. But it can be set to lower
values on some boards as long as false pen-ups are avoided. Lowering the
value increases the sampling rate (though current sampling rate is
sufficient for tsc operation). Hence charge delay has been made a DT
parameter.

Signed-off-by: Vignesh R <vigneshr@ti.com>
---
 .../devicetree/bindings/input/touchscreen/ti-tsc-adc.txt    | 13 +++++++++++++
 arch/arm/boot/dts/am335x-evm.dts                            |  1 +
 2 files changed, 14 insertions(+)

Comments

Hartmut Knaack Oct. 31, 2014, 9:09 p.m. UTC | #1
Vignesh R schrieb am 27.10.2014 12:08:
> The charge delay value is by default 0xB000. But it can be set to lower
> values on some boards as long as false pen-ups are avoided. Lowering the
> value increases the sampling rate (though current sampling rate is
> sufficient for tsc operation). Hence charge delay has been made a DT
> parameter.
> 
I would recommend to use a few colons to separate some thoughts. Also, limit to 80 chars per line would be beneficial. See inline.
> Signed-off-by: Vignesh R <vigneshr@ti.com>
> ---
>  .../devicetree/bindings/input/touchscreen/ti-tsc-adc.txt    | 13 +++++++++++++
>  arch/arm/boot/dts/am335x-evm.dts                            |  1 +
>  2 files changed, 14 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
> index 878549ba814d..ac62769e70e4 100644
> --- a/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
> +++ b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
> @@ -28,6 +28,18 @@ 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 affects the overall
> +			 sampling speed hence need to be kept as low as possible while
<...> speed, hence needs to be <...>
> +			 avoiding false pen-up event. Start from a lower value say 0x400
<...> pen-up events. Start from a lower value, like 0x400, and increase <...>
> +			 and increase value until false pen-up events are avoided. The
> +			 pen-up detection happens immediately after the charge step
<...> charge step, so this <...>
> +			 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 +48,7 @@ Example:
>  			ti,x-plate-resistance = <200>;
>  			ti,coordiante-readouts = <5>;
>  			ti,wire-config = <0x00 0x11 0x22 0x33>;
> +			ti,charge-delay = <0xB000>;
>  		};
>  
>  		adc {
> diff --git a/arch/arm/boot/dts/am335x-evm.dts b/arch/arm/boot/dts/am335x-evm.dts
> index e2156a583de7..80be0462298b 100644
> --- a/arch/arm/boot/dts/am335x-evm.dts
> +++ b/arch/arm/boot/dts/am335x-evm.dts
> @@ -641,6 +641,7 @@
>  		ti,x-plate-resistance = <200>;
>  		ti,coordinate-readouts = <5>;
>  		ti,wire-config = <0x00 0x11 0x22 0x33>;
> +		ti,charge-delay = <0xB000>;
>  	};
>  
>  	adc {
> 

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Vignesh Raghavendra Nov. 7, 2014, 5:48 a.m. UTC | #2
On Saturday 01 November 2014 02:39 AM, Hartmut Knaack wrote:
> Vignesh R schrieb am 27.10.2014 12:08:
>> The charge delay value is by default 0xB000. But it can be set to lower
>> values on some boards as long as false pen-ups are avoided. Lowering the
>> value increases the sampling rate (though current sampling rate is
>> sufficient for tsc operation). Hence charge delay has been made a DT
>> parameter.
>>
> I would recommend to use a few colons to separate some thoughts. Also, limit to 80 chars per line would be beneficial. See inline.

I will address this in v2

>> Signed-off-by: Vignesh R <vigneshr@ti.com>
>> ---
>>  .../devicetree/bindings/input/touchscreen/ti-tsc-adc.txt    | 13 +++++++++++++
>>  arch/arm/boot/dts/am335x-evm.dts                            |  1 +
>>  2 files changed, 14 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
>> index 878549ba814d..ac62769e70e4 100644
>> --- a/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
>> +++ b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
>> @@ -28,6 +28,18 @@ 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 affects the overall
>> +			 sampling speed hence need to be kept as low as possible while
> <...> speed, hence needs to be <...>
>> +			 avoiding false pen-up event. Start from a lower value say 0x400
> <...> pen-up events. Start from a lower value, like 0x400, and increase <...>
>> +			 and increase value until false pen-up events are avoided. The
>> +			 pen-up detection happens immediately after the charge step
> <...> charge step, so this <...>
>> +			 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 +48,7 @@ Example:
>>  			ti,x-plate-resistance = <200>;
>>  			ti,coordiante-readouts = <5>;
>>  			ti,wire-config = <0x00 0x11 0x22 0x33>;
>> +			ti,charge-delay = <0xB000>;
>>  		};
>>  
>>  		adc {
>> diff --git a/arch/arm/boot/dts/am335x-evm.dts b/arch/arm/boot/dts/am335x-evm.dts
>> index e2156a583de7..80be0462298b 100644
>> --- a/arch/arm/boot/dts/am335x-evm.dts
>> +++ b/arch/arm/boot/dts/am335x-evm.dts
>> @@ -641,6 +641,7 @@
>>  		ti,x-plate-resistance = <200>;
>>  		ti,coordinate-readouts = <5>;
>>  		ti,wire-config = <0x00 0x11 0x22 0x33>;
>> +		ti,charge-delay = <0xB000>;
>>  	};
>>  
>>  	adc {
>>
> 
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Patch
diff mbox

diff --git a/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
index 878549ba814d..ac62769e70e4 100644
--- a/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
+++ b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
@@ -28,6 +28,18 @@  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 affects 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 +48,7 @@  Example:
 			ti,x-plate-resistance = <200>;
 			ti,coordiante-readouts = <5>;
 			ti,wire-config = <0x00 0x11 0x22 0x33>;
+			ti,charge-delay = <0xB000>;
 		};
 
 		adc {
diff --git a/arch/arm/boot/dts/am335x-evm.dts b/arch/arm/boot/dts/am335x-evm.dts
index e2156a583de7..80be0462298b 100644
--- a/arch/arm/boot/dts/am335x-evm.dts
+++ b/arch/arm/boot/dts/am335x-evm.dts
@@ -641,6 +641,7 @@ 
 		ti,x-plate-resistance = <200>;
 		ti,coordinate-readouts = <5>;
 		ti,wire-config = <0x00 0x11 0x22 0x33>;
+		ti,charge-delay = <0xB000>;
 	};
 
 	adc {