Old suspend/resume issue likely root cause

[Glen Barber]

On Sat, Oct 17, 2015 at 11:57:05AM -0400, Eric McCorkle wrote:
> On 10/17/15 11:14, Glen Barber wrote:
> >On Sat, Oct 17, 2015 at 11:09:03AM -0400, Eric McCorkle wrote:
> >>A while back (in May or June or so), I was attempting to figure out why my
> >>laptop screen stayed blank on suspend/resume.  I posted some dmesg outputs
> >>and theorized that it might be something about the devices coming back up in
> >>the wrong order.  John Baldwin suggested I try doing
> >>hw.pci.do_power_suspend=0.
> >>
> >>I got tangled up with other projects and had to set it aside.  However, I
> >>now finally have more information:
> >>
> >>
> >>* hw.pci.power_suspend=0 does cause the screen to come back up properly.
> >>The network (wireless via iwm driver) needs to be re-initialized, but
> >>everything else seems to work properly.
> >>
> >>* Without hw.pci.power_suspend=0, the issue persists even when booting from
> >>EFI, so we can rule out some kind of legacy BIOS issue.  The issue manifests
> >>even with the experimental i915 driver, so we can rule out something with
> >>the efifb or VGA framebuffer drivers.
> >>
> >>
> >>Based on this, it looks pretty likely that the pci bus is the culprit. Any
> >>suggestions on where to look?
> >
> >What graphics chipset do you have?  I noticed with dumbbell's i915kms
> >update branch [1], suspend/resume now works for me with Haswell
> >graphics, whereas previously I would experience the same blank screen on
> >resume you report.
> 
> Intel i7-4700.  I tried suspend with the i915kms driver active, hoping that
> would do the trick, but it didn't work.
> 

I missed in your first email you mentioned the "experimental i915
driver."  Is this the driver update from the branch I linked to?
> 
> >(And I also see the iwm(4) reinitialization issue, as well.)
> 
> The workaround there is just to take netif, wpa_supplicant, dhclient, and
> rtsold down in rc.suspend and bring them back up in rc.resume.
> 

Yep, that's basically what I did to work around this.

> >[1] https://github.com/freebsd/freebsd-base-graphics.git branch
> >     drm-i915-update-38
> >

Glen

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