Serious problem with SATA LPM in F28 on Lenovo 50 series laptops

[Hans de Goede]

Hi All,

I'm sending this to the fedora-kernel and -devel lists
both to get the kernel team aware of this and because it
is not entirely clear to me how to best deal with this.

I guess we should get this added to the release-notes /
common-bugs page for F28, but I'm not sure what the
procedure is for that ?

I've just become aware that at least for some users
the use of SATA LPM in F28 causes the Lenovo 50
series laptops (confirmed X250, T450s G50-80) freeze/
hang hard under certain conditions when using SATA
LPM, independent of the disk used (*).

This is currently being tracked in:
https://bugzilla.redhat.com/show_bug.cgi?id=1571330

A known workaround is to add: "ahci.mobile_lpm_policy=0"
to the kernel boot command line.

Can someone help me to get this documented? Once we've
figured out what is going on I hope to be able to fix this
with a kernel update, but people may still need the
workaround to install Fedora 28.

Also if people are using Fedora 28 on a 50 series Lenovo
laptop without issues, please let me know. 3 independent
reports points to a common problem, but maybe there is
some other factor in play.

Regards,

Hans

*) So blacklisting disks by their model string which
is the normal way to workaround LPM issues does
not work.