[GUIDE] Fix touchpad after firmware update

[fotile96]

I am using a PocketBook InkPad Color (PB741), nevertheless, the following procedure should also apply to InkPad 3 (PB740) and possibily other devices.

It actually took me a whole night to figure out what was going wrong. Hope this could help guys having the same issue.

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How to reproduce the problem: Do an OTA or manual firmware update on a jailbroken PB740/PB741. The update will fail, after reboot, the touchscreen no longer works.

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Some obervations: The issue arose today after performing an OTA update. From PB's official site, I found 3 firmwares, respectively 6.5.2918, 6.5.1684 and 6.3.560. 6.5.2918, the latest one, turns out to be the OTA update target that just killed my touchscreen. I then tried to manually downgrade to 6.5.1684, but it didn't help. I also tried to downgrade to 6.3.560, but it said this firmware was too old and rejected flashing.

After a bit of googling, I found another firmware 6.3.917, which fixed the touchscreen after flashing.

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Cause of the problem:

After unpacking the update binaries of firmware 6.3.917 and 6.5.2918, I went through the update scripts related to touchpad firmware. It turns out that on
ver. 6.5.2918, there are two sets of touchpad firmwares for two different manufacturers, the updater will flash the correct firmware according to the value of device_touchpanel in the output of /bin/hwconfig. On the other hand, 6.3.917 only supports touchpads from one of the two manufacturers (we can speculate that PocketBook introduced a new brand of touchpad controller at some time in between these two firmware's anouncement).

On jailbroken devices, since the partition fingerprints changed, some update scripts will not get executed and the updater will return a update failure (though the whole flashing process actually suceeds, only some post-processing scripts return an error). One skipped update script that only presents in firmware 6.5.* tries to create a symlink for the touchpad kernel module according to the actual model. When the reader starts up, it will tries to load the touchpad module by this symlink. In a jailbroken device, the symlink does not exist thus the module does not load, and the touchpad dies.

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How to resolve the issue:

In order to have the touchscreen work on a recent firmware 6.5.*, it suffices to create the .ko symlink manually.

1. (Skip this step if you already have USB networking and SSH server on) Downgrade to a old firmware version, e.g., 6.3.917, so that the touchscreen is working. Jailbreak and root the device, enable USB networking and SSH server.

2. Upgrade to the latest firmware. The touchscreen will break down but we still have a root shell (via SSH over USB or wireless network)

3. SSH to the reader. run /bin/hwconfig to see the value of device_touchpanel. (On my PB701 I have device_touchpanel=21).
Run mount -o rw,remount /dev/root / to remount the root partition.
Run cd /lib/modules
If device_touchpanel=26, run ln -s ektf3908.ko tp.ko,
otherwise, run ln -s cyttsp5.ko tp.ko
Run reboot. Your reader will reboot, after it starts up again, the touchscreen should work.

[hombretranquilo]

This procedure worked like a charm on my rooted Inkpad 3 (PB740).

Latest firmware version with touchscreen working for Inkpad 3 is 6.5.1379. And the value of device_touchpanel is 21, too.

Hugh thanks, fotile96.

[nhedgehog]

Very good advice, thanks. Could you please ad in the thread title "on rooted devices" for others to find it better.

[Nnnatep]

Unfortunately I found this thread after I performed the update on my PB740-2...I can't figure out how to downgrade...found that I can try and install update again (power + left and right) but that fails the same way. I've tried connecting to a computer (and Android phone) but it seems like the device is waiting on approval to give control to another device.

Any ideas on how to downgrade or factory reset without being able to touch the screen?

[Valwit]

Originally Posted by Nnnatep

Any ideas on how to downgrade or factory reset without being able to touch the screen?

Probably a bit late for you, but anyway, for the next person that finds this:

download the firmware (from pocketbook.ch for example) unpack, connect the reader via usb, move the swupdate.bin to the root directory of the reader, turn it off, then on again and press the < and > button, then follow the dialog

[Red DAN]

Hello! Is there a way to get the sensor to work in a Pocketbook 628? The original has ED060XCG installed. I have ED060XH7 and ED060XCD, but the sensor does not work with them. I connected to the book via SSH (jailbreak and root obtained), and determined that device_touchpanel=23
Please tell me what needs to be done next in order for one of my screens to work correctly, if possible.

[ya5676]

Hi, how can it possible downgrade firmware from 6.5.XXXX to 6.3.XXX on PB741?

[nomoi]

It seems I'm late to the party..

Originally Posted by hombretranquilo

This procedure worked like a charm on my rooted Inkpad 3 (PB740).

Latest firmware version with touchscreen working for Inkpad 3 is 6.5.1379. And the value of device_touchpanel is 21, too.

Sadly not for me. I'm using the mentioned sw_20211222_U740_6.5.1379_user.zip, but while trying to downgrade I get:

               Firmware update
swupdate version: Dec 22 2021,11:49:33
Searching for update image...
Updating from internal memory
Device serial number: *redacted*
Checking update image...
Found FW for device model: PocketBook740
Update image: MD5 sum mismatch
The device will turn off in few seconds

It seems like the downgrade doesn't work. Do I need to change a MD5 in some file?

Please, any help is highly appreciated!! Thanks!

[nomoi]

Originally Posted by nomoi

Sadly not for me. I'm using the mentioned sw_20211222_U740_6.5.1379_user.zip,

In the meantime I had some success debricking my PB740 with sw_20190709_U740_5.20.1010_user.zip and the awesome post @fotile96 gave at the top:

mount -o rw,remount /dev/root / 
cd /lib/modules
grep -q 'device_touchpanel=26' && run ln -s ektf3908.ko tp.ko || ln -s cyttsp5.ko tp.ko
reboot

Big thanks to you, @fotile96, you're awesome!! How did you even find these?