Custom Kernel for MT6739 Smartwatches

none · July 28, 2020, 6:37pm

Summary:

This is a reversed or re-created kernel source for the MT6739 Smartwatches, this is mostly intended to have a reference source that might be able to support future development.

Edit:
No longer maintained.

Giorgos_Tsarouchas · July 28, 2020, 7:12pm

Maybe it’s a silly question, but I have to ask… What is the potential of a custom rom? Forbidden functionalities like bluetooth calling?

SERZAO · July 28, 2020, 7:44pm

Prime SE also ? @none

none · July 28, 2020, 8:15pm

@Giorgos_Tsarouchas
Primarily a more recent Android version with all included fixes and security updates.

@SERZAO
It looks identical to the Prime except for ram/storage, you might try it.
But be sure to create a backup / get a copy of the prime se firmware.

Giorgos_Tsarouchas · July 28, 2020, 8:29pm

OK sir, this looks promising

Bozley · July 29, 2020, 2:18am

Great work! Will this work without overwriting the user area? If so I will start trying this immediately.

none · July 29, 2020, 2:37am

Download SP_Flash_Tool, extract it and launch flash_tool.exe
Click on ‘choose’ located next to ‘Scatter-loading File’ and select ‘MT6739_Android_scatter.txt’ from the extracted kernel archive:

Click on ‘Download’
Turn your Smartwatch off.
Connect your Smartwatch with the USB data cable.

It should start the flashing process now, don’t interfere with the device until the process is done.

pablo11 · July 29, 2020, 9:13am

@none Thanks for your work and thanks for posting this in the right place

Bozley · July 30, 2020, 2:28am

So far so good, no problems or differences that I’ve noticed. Is there something in particular we should try to stress test?

pablo11 · July 30, 2020, 7:08am

I’m actually wondering what benefits you will be getting from this kernel?
@none is there something in particular that people will notice if they flash this kernel?

I’m curious because we have had them before and tweaked governors and other things but no benefit was ever realised…

Great stuff by the way and I’m very grateful, but what do you think?
Better battery life or something else?

none · July 30, 2020, 11:55am

@Bozley
Thanks, most important is that everything is working correctly (accelerometer, cameras, heart rate, sim, gps, charging/discharging, battery life).

@pablo11
As mentioned in the first post:

Due to the nature of reversing there could be missing features or other problems that can only be tracked down by testing.

This is mostly intended as ‘reference’ source that can refered to when migrating to a higher kernel version.

pablo11 · July 30, 2020, 12:18pm

Ah ok,
I certainly didn’t want to give the wrong impression because I am very grateful that you have taken an interest.
Not only in working on these sources with the Openwatch team - but also posting your work here as well.
We have worked with the Openwatch guys for quite a while now.
Iscle is a moderator here as well, for example.
When he has the time
Anyway, welcome aboard

none · July 30, 2020, 6:18pm

Thanks, i was looking for a small android / embedded device to tinker with and those full android smartwatches were ideal.

Yes, Iscle and Deadman did a lot of awesome work for the OpenWatchProject, make it possible in the first place and can be credited as well.

Bozley · July 31, 2020, 10:50pm

While listening to and navigating the YouTube Music app my Prime crashed. I had to hold the power button for about 30 seconds to boot. I got it to happen 2 more times so it’s a repeatable bug. After reverting to the original kernel this problem hasn’t happened again.

none · July 31, 2020, 11:04pm

Can you provide me a log when this happens?
Here is small archive that includes adb.exe and a script ‘Logfile.cmd’ that will pull the last kernel log from the device (usb-debugging needs to be enabled).

Bozley · August 1, 2020, 3:08pm

Here you go

none · August 1, 2020, 4:32pm

Thanks for the log, i made a new build that hopefully fix the music crash issue: PRIME #2
I also made some slight changes to the heart rate sensor, please check if it’s working correctly, thanks.

Bozley · August 2, 2020, 5:15pm

The HRM is not working - the testing app says “test failed”. I’m pretty sure it was working with your first kernel. I also had a crash. Same situation but it took longer to crash than before. Here’s the log.

none · August 2, 2020, 7:36pm

Thanks again for the logfile, it is unfortunately still the same problem.
Seems to be caused by the ‘fpsgo’ driver and a missing proprietary kernel module (which isn’t included).
It’s intended to boost gaming performance, but i don’t think this has a lot of use for our smartwatches, so i turned it off.

Anyway, here is a new build that should fix this issue: PRIME_#3

Bozley · August 3, 2020, 5:40pm

The crashing bug does seem to be fixed, and HR is working again. I tested every feature* (though not always extensively) and everything seems to be working correctly.

*Except phone features; I don’t have a SIM card in my Prime.