[Android Q&A, Help & Troubleshooting] KeepGood:
Hi all,

I'm wondering if you guys can help me get this head unit back up and running (properly). :)

The story so far...

I bought a cheap head unit for a project car (first Android head unit I've had). When I received it, it actually ran REALLY well, everything was super smooth, very responsive. There was a problem though, all of the internal storage was read only, nothing was left for app space. They had also removed the options to format an SD Card as internal storage so I couldn't install anything. I got to looking for a replacement firmware. After a tonne of reading I was finding it was pretty much a clone of a Joying head unit, at least from a spec and software point.

This is the unit...

*ebay.co.uk/itm/7-Quad-Core-Android-6-0-WiFi-1DIN-Car-Radio-Stereo-BT-GPS-Navi-MP5-RDS-Player/253882611489?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

I had used the Joying Tools to root it, it actually failed but strangely after a restart the FS was R/W. Only a few hundred meg was used :D I should've stopped there but yeah, I didn't. The more I read, the more I thought it was just a Joying unit, in a physically different package and for the most part it is. It seems like the minor differences are what is causing me problems. My touch screen now doesn't work :)) I took me ages to notice too, I'm not actually sure at what point of my messing around it happened, I had a keyboard and mouse plugged in.

The screen itself is fine (undamaged), from what I can see the driver is having problems. After a bit of digging I was starting to think the driver wasn't installed for it. I could see the devices listed in programs like Hardware Info but I couldn't see any modules loaded for it. I was thinking that the new firmware didn't have the same modules so my plan was to recompile the drivers from source. I got that done and when going to install them, I saw a load of errors with dmesg. The I2C controller seem to be running but is having problems, and drivers for the controller and touchscreen do seem to be there. dmesg is showing...

start check gt9xx_i2c

<<-GTP-INFO->> Guitar reset

i2c i2c-3: xgold_i2c_error_reg_status, device: 0x41 ERR_INT 0x30 recvd msg len: 1, state: 1

<<-GTP-ERROR->> I2C Read: 0x8040, 2 bytes failed, errcode: -121!

There is a lot in there, it repeats a lot but that's what stands out, I'll need to find something to make reading the dmesg output a bit clearer but overall, you can see the communication with the touchpanel trying to happen but isn't. White reading the porting documentation for the GT9xx driver I found out that you have to tell it what GPIO's are going to be used for reset and irq, maybe some others. I'm assuming that is GPIO's from the MCU but I'm not sure, I'm still a bit hazy on how the parts of these units talk to each other. I'm thinking the drivers in the Joying firmware are configured for addresses and GPIO's different from this unit so communication with the Touchpanel isn't working (being hardcoded into the driver).

Info about the system...

Manufacturer: ReakoSound (maybe, its not printed on the box or unit but raking around it seems to be them that makes it)

Model: RK-A712

CPU: Rockchip Sofia

RAM: 1GB

ROM: 16GB

Touch: Goodix GT9157

OS: Android 6.0.1

Does anyone have any ideas about how I can get the screen up and running or does anyone have one of these units? Everything else does seem to be running perfectly, the unit is running the GTX rom for Joying Sofia head units right now.

Thanks in advance :)