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#1 2021-11-25 03:39:17

napion
Member
Registered: 2015-04-11
Posts: 5

udevadm prints out constant changes to typec port0

I was trying to understand why plugging in a AC supply increases the laptop temperature. So I ran 'udevadm monitor -u' to see what rules are being fired. Interestingly I saw this output:

> udevadm monitor -u   
monitor will print the received events for:
UDEV - the event which udev sends out after rule processing

UDEV  [348.291145] change   /devices/platform/USBC000:00/typec/port0 (typec)
UDEV  [348.609435] change   /devices/platform/USBC000:00/typec/port0 (typec)
UDEV  [350.339523] change   /devices/platform/USBC000:00/typec/port0 (typec)
UDEV  [350.456082] change   /devices/platform/USBC000:00/typec/port0 (typec)
UDEV  [351.276070] change   /devices/platform/USBC000:00/typec/port0 (typec)
UDEV  [351.582771] change   /devices/platform/USBC000:00/typec/port0 (typec)
UDEV  [351.789541] change   /devices/platform/USBC000:00/typec/port0 (typec)
UDEV  [352.189421] change   /devices/platform/USBC000:00/typec/port0 (typec)
UDEV  [352.389409] change   /devices/platform/USBC000:00/typec/port0 (typec)
UDEV  [352.696088] change   /devices/platform/USBC000:00/typec/port0 (typec)
UDEV  [352.902656] change   /devices/platform/USBC000:00/typec/port0 (typec)
UDEV  [353.209405] change   /devices/platform/USBC000:00/typec/port0 (typec)

There are about 3-4 events/sec related to some typec port0 changes. This laptop (ASUS GU502LV) has a single usb-c port and nothing is connected to this. Is this normal?

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#2 2021-11-25 16:45:50

ewaller
Administrator
From: Pasadena, CA
Registered: 2009-07-13
Posts: 17,970

Re: udevadm prints out constant changes to typec port0

My guess is that it is permitting the USB-C ports to allow USB devices to negotiate for more power when the system is on shore power.   Do those messages continue?

Other things that could be going on -- Your processor and perhaps GPU may have transitioned from a low power state to a higher performance state.
Also, your power supply will certainly be working a bit harder as it is not only powering the computer (which is ramping up its demand), it is also going to be charging the battery at a fairly high rate.
Finally, batteries get warm when they are charged as the charging efficiency is < 1.


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