-----Original Message-----
From: Mark Rutland [mailto:mark.rutland@arm.com]
Sent: 28 May, 2015 16:22
To: Tirdea, Irina
Cc: Dmitry Torokhov; Bastien Nocera; linux-input@vger.kernel.org; devicetree@vger.kernel.org; linux-kernel@vger.kernel.org;
Purdila, Octavian
Subject: Re: [PATCH 6/9] input: goodix: write configuration data to device

On Thu, May 28, 2015 at 01:47:42PM +0100, Irina Tirdea wrote:

quoted

Goodix devices can be configured by writing this information
to the device at init. The configuration data can
be provided through the ACPI/device tree property
"device-config". If "device-config" is not set, the default
device configuration will be used.

Signed-off-by: Octavian Purdila <redacted>
Signed-off-by: Irina Tirdea <redacted>
---
 .../bindings/input/touchscreen/goodix.txt          |   5 +
 drivers/input/touchscreen/goodix.c                 | 143 +++++++++++++++++++++
 2 files changed, 148 insertions(+)

diff --git a/Documentation/devicetree/bindings/input/touchscreen/goodix.txt

b/Documentation/devicetree/bindings/input/touchscreen/goodix.txt

quoted

index 7137881..9e4ff69 100644

--- a/Documentation/devicetree/bindings/input/touchscreen/goodix.txt
+++ b/Documentation/devicetree/bindings/input/touchscreen/goodix.txt

@@ -15,6 +15,11 @@ Required properties:
  - irq-gpio		: GPIO pin used for IRQ
  - reset-gpio		: GPIO pin used for reset

+Optional properties:
+
+ - device-config	: device configuration information (specified as byte
+			  array). Maximum size is 240 bytes.

Generally we frown on passing opaque data.

What exactly is encoded in device-config? The description is very vague.

Does this correspond to anything in a data sheet or manual?

Yes, it is configuration data described in chapter 6.2. b of the datasheet: 
https://drive.google.com/folderview?id=0BxCVOQS3ZymGfmJyY2RKbE5XbVlKNlktVTlwV0lxNEdxd2dzeWZER094cmJPVnMxN1F0Yzg&usp=sharing.
This includes things like x/y resolution, maximum touch numbers supported, 
interrupt flags, various sensitivity factors. 

I should have included a link to the datasheet in the commit message - will do that in v2 for all patches.

I did consider writing this as firmware, but it seems that some Goodix touchscreens have a
real firmware they need to write in addition to this configuration data.
If there is a better way to do this, please let me know and I will change it.

Thanks,
Irina

Mark.