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On Fri, Mar 2, 2018 at 10:26 PM, Richard Wilbur richard.wilbur@gmail.com wrote:
On Mar 1, 2018, at 20:30, Luke Kenneth Casson Leighton lkcl@lkcl.net wrote:
Sent from my iPhone
On Thu, Mar 1, 2018 at 9:46 PM, Richard Wilbur richard.wilbur@gmail.com wrote:
It looks to me like the fastest way to test the GPIO lines connected on the micro-desktop board to VESA_SCL and VESA_SDA would simply be to connect a VGA monitor to the micro-desktop and make sure it is properly detected and a test image looks right on it.
yep, pretty much... with one slight fly in the ointment: the SCL and SDA lines are straight GPIO and will need a bit-banging I2C linux kernel driver. once that's configured, doing i2cdetect _should_ be enough to test the circuit, although scanning the data and running read-edid on it would be awesome and amazing: it would mean being able to *really* do proper VESA detection.
Is someone already working on that?
no.
Sounds like we need the device tree for the micro-desktop to be populated.
patches to linux mainline are needed to include the ability to have devicetree fragments before that can happen.
however... the A20 linux sunxi mainline source is *not 100% functional* so it's kinda moot.
If we did it for micro-desktop v1.7 it would be something to build off for micro-desktop v1.8 and also a good place to begin for the laptop.
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.)
i found a random driver somewhere for I2C - don't know about the linking to userspace / DDC.
If none of this is underway I'll continue mapping things out so we can create the device tree for the micro-desktop.
that would be useful... *if* the A20 linux sunxi mainline source supports 100% of the functionality of an A20.
If I remember correctly we also should create a device tree for the DS-113 v2.7.4 and v2.7.5?
again same caveat.... *thinks*.... yeah.
I'd be happy to work on that if you think that is the highest priority right now. It sounds like it will help both testing and deployment.
let me think...
two conditional things need to happen:
1. the A20 sunxi mainline code needs to have 100% functionality support for ALL hardware
2. the "devicetree fragment" patch also needs to be confirmed as mainline.
then it's useful.
l.