hpet vs suspend to ram

[Konstantin Belousov]

On Thu, May 03, 2018 at 11:40:24AM +0300, Andriy Gapon wrote:
> 
> Just want to share a strange problem that I see on one system.
> 
> If I use HPET as an eventtimer, then after a seemingly successful resume
> the system starts to act weird.  It becomes unresponsive for periods of
> time, then it gets more normal, then it's sluggish, then unresponsive
> again.  After some time struggling the system finally locks up entirely.
> 
> I see this problem both with FreeBSD and Linux (tested with Ubuntu 16
> and 17).
> 
> If I use any other timer hardware, then everything is okay.
> Also, if I switch to HPET after a resume, then it's okay too.
> I tried uncommenting the code in acpi_hpet.c that disables the HPET
> before suspend, but it didn't change anything.
> 
> I suspect that the problem is with SMM code, but don't know how to check
> it or whether it would make any difference.
> I also tried disabling various devices (e.g. USB) through BIOS config, but that
> also didn't help.
Did you tried to clear comparators, besides disabling the HPET ?

> 
> The system uses Asus M4A89GTD PRO motherboard.
> 
> -- 
> Andriy Gapon
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