blacklisting i2c_i801 breaks trackpad detection on Acer C710, plus other hardware

[Ewan]

file:
/etc/modprobe.d/blacklist.conf

contains the text:
# causes failure to suspend on HP compaq nc6000 (Ubuntu: #10306)
blacklist i2c_i801

note: actually the correct LP id appears to be https://bugs.launchpad.net/bugs/16602

after short discussion at https://answers.launchpad.net/ubuntu/+source/kmod/+question/269329 I'm raising this as a bug

as well as preventing trackpad detection in the case of Acer C710, there is an older bug open at https://bugs.launchpad.net/bugs/857175. Here this same blacklist entry breaks some functionality for a Thinkpad T41. In turn, that bug includes a reference to another source (http://permalink.gmane.org/gmane.linux.drivers.i2c/9120) where the blacklist entry has required support effort.

lsb_release -rd
Description: Ubuntu 15.04
Release: 15.04

apt-cache policy kmod
kmod:
  Installed: 18-3ubuntu1
  Candidate: 18-3ubuntu1
  Version table:
 *** 18-3ubuntu1 0
        500 http://au.archive.ubuntu.com/ubuntu/ vivid/main amd64 Packages
        100 /var/lib/dpkg/status

[Javier Vilalta (jvilalta)]

I have found that iTCO_wdt doesn't work without previously loading i2c-i801 (you can see a pair of references in http://linux-kernel.2935.n7.nabble.com/PATCH-0-5-iTCO-wdt-Add-support-for-Intel-Sunrisepoint-td1160031.html and in https://lkml.org/lkml/2016/9/10/157) As it's blacklisted, it doesn't load even when putting it on /etc/modules.
As stated by OP on launchpad discussion, it seems that the original decission to blacklist i2-i801, as correct as it was in its moment, seems to be creating more problems now for modern systems.

[Olivier Louvignes (olouvignes)]

Can confirm that I currently have this issue when trying to load the iTCO_wdt at boot.

We should have a way to whitelist back a module without having to edit the blacklist files.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.