[PATCH 4/8] ARM: dts: sun8i: Add touchscreen node for sun8i-a23-gt90h

[Hans de Goede]

Hi,

On 22-08-16 20:30, Maxime Ripard wrote:
> On Mon, Aug 08, 2016 at 09:43:14PM +0200, Hans de Goede wrote:
>> The gt90h tablet has a gsl3675 touchscreen, add a dt node describing it.
>>
>> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
>> ---
>>  arch/arm/boot/dts/sun8i-a23-gt90h-v4.dts | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/sun8i-a23-gt90h-v4.dts b/arch/arm/boot/dts/sun8i-a23-gt90h-v4.dts
>> index f27ebbb..da55b5a 100644
>> --- a/arch/arm/boot/dts/sun8i-a23-gt90h-v4.dts
>> +++ b/arch/arm/boot/dts/sun8i-a23-gt90h-v4.dts
>> @@ -53,6 +53,14 @@
>>  	status = "okay";
>>  };
>>
>> +&gsl1680 {
>> +	compatible = "silead,gsl3675";
>> +	touchscreen-fw-name = "silead/gsl3675-gt90h.fw";
>
> That's not documented anywhere, and looks really suspicious.

Ugh, that should have been in:

Documentation/devicetree/bindings/input/touchscreen/silead_gsl1680.txt

But somehow it is not (I believe it was there in earlier revisions of
the patch), I'll send a patch to fix this.

About it being suspicious, this is not really firmware it is a bunch
of configuration data / lookup tables for the controller which tell
it in which order the touchscreen horizontal / vertical sensor
lines are connected to its sense pins, and what values to send
for finger x% between line z and line z+1, which differs per
tablet model, since not all tablets use the same digitizer.

Regards,

Hans