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#1 2020-03-23 21:48:26

Registered: 2020-03-23
Posts: 1

The touchpad consumes a lot of CPU and drains the battery

I have Asus X756UQ laptop. I installed Arch and Windows 10 a few days ago. 
I noticed that on Arch the battery discharges much faster.
This is what powertop shows:

Summary: 3361.3 wakeups/second,  0.0 GPU ops/seconds, 0.0 VFS ops/sec and 41.0% CPU use

Power est.              Usage       Events/s    Category       Description
6.90 W      6.2 ms/s     1744.0      Interrupt      [17] idma64.1
1.55 W     10.7 ms/s     365.0       Process       [PID 406] [irq/109-ELAN100]
1.50 W      8.6 ms/s     376.8        Timer          tick_sched_timer

[17] idma64.1 - it causes high cpu usage. Usually interval is not 6.2 ms/s but about 600 µs/s(I don't know if it is important). This problem exists only when I use touchpad.
To be more specific, even if I turn off touchpad using: "xinput disable 'Elan Touchpad' ", when I touch touchpad this problem also occurs, but when I don't it immediately disappears.
I tried both: libinput and synaptics drivers but effect is the same.   
I had following message in journalctl -k | grep ELAN

Mar 23 01:47:23 ArchSUS kernel: elan_i2c i2c-ELAN1000:00: i2c-ELAN1000:00 supply vcc not found, using dummy regulator
Mar 23 01:47:23 ArchSUS kernel: elan_i2c i2c-ELAN1000:00: Elan Touchpad: Module ID: 0x0005, Firmware: 0x0004, Sample: 0x000d, IAP: 0x000e

So acording to Arch libinput wiki I added option psmouse elantech_smbus=0 to /etc/modprobe.d/psmouse.conf but it didn't help :\

I checked whether this problem exist also on Ubuntu Live and powertop showed exactly the same problem... I started to think that it is hadware issue, but when I use Windows 10 everything is fine and CPU doesn't freaks.
Also I have to add that touchpad is working properly on both Arch and Windows, there is no problem with multitouch or anything like this.

What should I do?
Btw. I am newbie and I don't know if I'm posting in the right forum.

Last edited by Matix (2020-03-23 22:25:35)


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