[Arm-netbook] Testing: GPIO

[Richard Wilbur]

On Mar 2, 2018, at 15:43, Jonathan Neuschäfer <j.neuschaefer at gmx.net> wrote:
>> On Fri, Mar 02, 2018 at 03:26:32PM -0700, Richard Wilbur wrote:

[…]
> I'm not actively working on any of this, but I'm interested in the
> devicetree side of things.

To what does your interest in devicetree extend?  Are you interested in helping create the devicetree mappings for EOMA68 hardware, or following developments, etc.  How would you like to be involved?  Thank you for imparting your knowledge below.

>> From what I'm hearing, once the device tree is ready we could work on
>> "automagically" configuring the VESA DDC driver to bit-bang the
>> correct GPIO pins. Does the bit-banging VESA DDC driver exist already?
>> (I wrote a bit-banging I2C driver in VxWorks at a previous position so
>> the topic is not foreign.)
> 
> Mainline Linux has a driver[1] for I2C-over-GPIO. It's been there since
> 2.6.22, albeit initially without devicetree support, which came in 3.4.
> 
> There's also a generic devicetree binding[2] for I2C-over-GPIO in
> Linux's Documentation/devicetree/bindings directory.

That's wonderful news!  So with the devicetree for the micro-desktop we should be able to setup the I2C driver.  Next question:  has anyone created a VESA DDC driver that will get the EDID from any connected monitor given when given access to an I2C device (as exposed by our bit-banging I2C driver).

VESA DDC is a standard that specifies a protocol on top of I2C for obtaining monitor information (supported resolutions and timings, color gamma, etc.).

>> If none of this is underway I'll continue mapping things out so we can
>> create the device tree for the micro-desktop.  If I remember correctly
>> we also should create a device tree for the DS-113 v2.7.4 and v2.7.5?
> 
> What is DS-113?

EOMA68-A20 the CPU card.