[ROM][4.4.4] Cyanogenmod-11 for Lenovo A2109 (20160510)

[PJBrs]

Very bad news, my tablet just died... It's not the usb port and the battery seems okay too. It might be the system board.

 

[tasinofan]

what a terrible situation!

 

[jam97]

What happened PJBrs?

 

[PJBrs]

What happened PJBrs?

I have no idea, apart from that it suspiciously coincides with I had just begun using a new kernel about a week before. Then again, apart from the kernel code for the charger, I don't think I was using any code that was very different from stock Lenovo sources. Basically, I had just put the tablet on the charger and the next morning it didn't wake up. I also tested the power button to rule out a mechanical problem, but I did find the pins on the power button connector and registered that it pulled low some voltage somewhere when pressed.

I think it must have been all this booting and rebooting, keeping it connected to charger or usb cable for prolonged periods.

 

[yaka]

 

[jam97]

Sorry for that.

 

[PJBrs]

Well. I'm wondering what to do about this. I want a new tablet. I do not want it to be obsolete as A2109, but then again, I don't want it to be expensive, like Nexus 9, and the development work for A2109 at least is interesting work... Also, all the cheapy-cheapy tablets appear much harder to dev for, many don't even have publicized kernel sources (GPL violations, the lot).

 

[jam97]

Thank you so much for what you did for us, I think Samsung tablets are good.
Have you tried to port Lollipop for a2109 tablet?
Any simple guide on how to add new I/O schedule to a kernel?
Best Regards,

 

[PJBrs]

Well, I'm not decided yet, I might try to repair mine. I just remembered that, with KitKat, it was the only device that worked reliably with dlna.

Regarding the kernel, it's a matter of finding a kernel patch for the scheduler you want that applies to 3.1. Look for grouper kernels and other tegra3 devices that use 3.1. The difficulty is in finding the right patch, the rest is easy.

 

[joebine]

Hi PJBrs,

Sorry to see that your tablet had died but thank you for the hard work you had done for our tablet.

If you want to try to fix your tablet, here is a site that describe ho to fix the A2109:
Lenovo IdeaTab A2109 Repair

 

[PJBrs]

Okay, I'm back in business, upgrading my new (second hand) A2109 right now.

Hi PJBrs,
If you want to try to fix your tablet, here is a site that describe ho to fix the A2109:
Lenovo IdeaTab A2109 Repair

Thanks! I used the hardware maintenance manual, which is also a very good resource.

Anyway, development is set back a bit for now, I want to use the parts of the new tablet to find out what's wrong with the old one first, and buy a replacement part to have two devices instead of one. But stay tuned for updates

 

[profeet]

@PJBrs it's a very good news. We look forward to new updates.
Thank you very much for development!!!

 

[PJBrs]

Okay, the mainboard indeed was the culprit. Just ordered a new one from Ebay, which should add one tablet to our collection

 

[jam97]

So, what do you think caused this damage to the mainboard, PJBrs?

 

[PJBrs]

So, what do you think caused this damage to the mainboard, PJBrs?

I have no idea. Like I said, it suspiciously co-occurred with my testing a new kernel, but then again, I have a hard time imagining how my kernel would damage this board, except maybe the battery. But the battery is still in good order, so there... This the reason that I bought a new system board, I want to safely be able to test my new kernel without pushing damaging software to users or damaging my new tablet.

(I have not uploaded this kernel branch. It is based on the nvidia kernel commit is most common to lenovo sources - 92f2d2099e3411dfa1966e8ead58dc5654f3124c. I only patched the tegra-board files and the sound driver, the rest was additions only, that is:

• two camera drivers s5k5cag and mt9m114
• battery driver bq27541
• power button and rotation lock button
• touchscreen ft5x06
• light sensor jsa1127
• accelerometer lis3dh

That's a lot cleaner than just dumping a load of source all over the kernel, and it offers cleaner chances to experiment with later nvidia changes or google changes.)

One thing remotely close might be my change to the CPU governor settings to fix bluetooth sound stuttering, but, again, I see the CPU enter the lowest states most of the time when the screen is off, so I don't see how that would cause this.

Really, the only thing that makes sense is that it finally gave up after a huge amount of reboots, kernel flashes and rom flashes. For all I know, this might have damaged the memory of the boot partition. Who knows...