What is the significance of getting access to the UART module?
Helpful but not a major blocker, there are other ways to get data off the device and its common to have a serial via the usb connection if you have a special cable.
MediaTech is selling a dev board with the X20 on it.
https://www.mediatek.com/products/developme...-board-96boards
The dev board does not mention any GSM connectivity, although the X20 it self does
https://www.mediatek.com/products/smartphon...t6797-helio-x20
Our dev board is essentially the gemini itself, there will be enough differences that it will likely not be much of a gain to use a working dev board as these boards allow you to start software work before you have the hardware. as the gemini is delivered already we have the hardware to test on.
I have not played with a SoC dev board before. Does anyone have experience with a SoC api?
Do they give a well documented library that gives us full access to their hardware?
Why do companies like this not want to freely give out a well documented library for users to play with? I would like to be able to just go on their website and download this library.
How does a company like Planet Computers go about developing for a SoC? They have to sign NDA? A non public dev board for the X27 exists or the X family is so similar you just use the same code.
When you say there is no upstream support, what this means is that MediaTech has not submitted any code/drivers to the linux kernel that drives their hardware. Is this correct?
Please help me understand how this scene works.
Kernel development is a bit different to userspace development, there is no 'library' that we can drop in and use, and the quality of most chip vendors code is questionable at best. The major problems are that the 3.19 kernel is real old and has diverged significantly, in addition the android 3.19 kernel had a large amount of custom written parts in it that diverged from the base 3.19
There are some things we can leverage cross vendor, eg cpufreq stuff and some graphical/GPU stuff as this is mostly licesed cores that only really diffre by locaiton in memory. In addition the armv8 series came up with a spec that is sort of like the PC-XT spec and standardizes armv8 designs allowing a lot of power and boot code to be reused. the real issues will include the following
* Board specif cbring up
* memory timings
* SD reader driver
* usb type c drivers (still in flux in 4.15, will not really be stable 100% complete till 4.18 or end of this year)
* wif drivers (MT7610U/USB is supported but not confirmed this is the chip we use)
* 4g modem
* Keyboard driver
* IIO Sensors (gyroscope/compuss)
even once we do get access to the source (if we do) this si not going to be a simple copy and paste job and will likely be without vendor documentation
I would have paid 2x the current costs for an exynos based chip as i know samsung upstreams their drivers in mainline before devices hit production making ti a very simple affair to get a newer kernel working. there also would not be these limitations with the usb ports and chargng/displaying whihc is one of the major points of contention for me.
(mainline means that the kernels on kernel.org contain the drivers required to run the board)
still poking things at my end and hope to come up with a todo list soon but if anyone has a link to the kernel sources and is willing to share let me know as there are some drivers i would not mind having on hand
