On 08/21/2015 03:47 AM, Michael Welling wrote:

On Thu, Aug 20, 2015 at 05:41:30PM +0530, Vignesh R wrote:

quoted

On 08/19/2015 11:38 PM, Michael Welling wrote:

quoted

On Wed, Aug 12, 2015 at 01:44:22PM -0500, Michael Welling wrote:

quoted

On Wed, Aug 12, 2015 at 11:56:36AM +0530, Vignesh R wrote:

quoted

Hi Michael,

+ Dmitry

On 08/12/2015 12:15 AM, Michael Welling wrote:

quoted

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 <redacted>
---
 .../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.
 

Since open-delay is per step, is it not better to allow specifying
open-delay per step like ti,chan-step-opendelay of adc? This will help
control open-delay for all the four wires.

Do you see any reason why you would want a different delay for each step of
the conversion on the same touchscreen?

Sorry for the delay,

I haven't seen different delays being used for different channels on
4-wire TSC ( not sure of 5-wire or 8 wire designs). Since this is DT
change, I just wanted to make sure more flexibility is provided.

quoted

quoted

The user would need to know the number of steps what each of the steps do.

What I was thinking was making open-delay configurable per channel (one
entry for X+, X-, Y+, Y-).

For example, for a 4-wire TSC:
ti,chan-open-delay = <0x30 0x100 0x20 0x10>; /* for X+, X-, Y+, Y- */

What about the readings for the pressure?

Sorry, I was confused with channels and co-ordinate readouts.

Each of X, Y and pressure(Z) readouts will correspond to certain tscadc
steps. So, what I have in mind is:

ti,open-delay = <0x30 0x100 0x20>; /* for X, Y, Z */

For Steps that represents X co-ordinate readouts set opendelay = 0x30.
For Steps that correspond to Y co-ordinate readouts set opendelay =
0x100 and similarly for 0x20 for Z.

This is will provide flexibility to configure open-delay independently
for X, Y and Z


-- 
Regards
Vignesh