[Pie] [xiaomi] Use persist.sys.phh.xiaomi.dt2w prop to control DT2W

[cheah]

On stock kernel, the /proc gesture nodes are created to control DT2W
whyred: https://github.com/MiCode/Xiaomi_Kernel_OpenSource/blob/tulip-p-oss/drivers/input/touchscreen/lct_tp_gesture.c#L98
daisy: https://github.com/MiCode/Xiaomi_Kernel_OpenSource/blob/daisy-p-oss/drivers/input/touchscreen/gt917d/gt9xx.c#L1795

We can write "1" to these /proc nodes to enable DT2W and "0" to disable it

Related PR: phhusson/treble_app#21

[phhusson]

You'll need to tell me on what it has been tested. I've been told that some device have /dev/input dt2w control but not /proc.
Also, please note that opensource Xiaomi kernel DO NOT MATCH the actual production kernels.

I'd like to keep the /dev/input at least as fallback if no node has been found

[cheah]

Testes on whyred as well.
I'll amend the related PRs to keep the /dev/input first.

[cheah]

Done.
Tested on whyred with both OSS kernel and stock kernel on P Vendor.

[phhusson]

FWIW I can confirm my Mi 9 (cepheus) doesn't have any of those /proc nodes, so I confirm the /dev/input is needed

As for proc_dt2w_gesture, please don't do it with genfscon, but do it in rw-system.sh with chcon.

genfscon conflicts are not resolved, which means that if vendor has a genfscon proc proc_dt2w_gesture with another label/context, the device will simply not boot (or reboot to bootloader in stock AOSP, reboot to recovery in my GSI)

[phhusson]

Except for that, good for me. Feel free to bother me more to have this merged

[cheah]

Hi @phhusson, thanks for the tips about genfscon conflicts! However I have no idea how to fix this now since we can't chcon on /proc 😞 Maybe we should just forget the whole idea about setting DT2W thru proc node?

[phhusson]

See 552f710 I have a known issue that this is dangerous because it's possible to inject shell commands, but I'll fix it later Le sam. 21 mars 2020 à 13:33, Michael Cheah <notifications@github.com> a écrit :

…

Hi @phhusson <https://github.com/phhusson>, thanks for the tips about genfscon conflicts! However I have no idea how to fix this now since we can't chcon on /proc 😞 Maybe we should just forget the whole idea about setting DT2W thru proc node? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#139 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAA4OUTBRHCXMFAFDQHNALRISX23ANCNFSM4KAW75UA> .

[cheah]

Ok, what do you think about this: cheah@e016ce1? If it looks good to you then I'll update the PR and TrebleApp.

This way we can even remove the sepolicy for allow system_app input_device since it's no longer needed.

[cheah]

TrebleApp will look like this: cheah/treble_app@7b6789b

[cheah]

Fixed based on comments and also ran it thru shfmt & shellcheck. Please help to take a look again 😄

PR for Android 10 branch: #146
TrebleApp: phhusson/treble_app#21

[cheah]

@phhusson bump in case you missed it 🙂