Re: [PATCH] i915 / PM: Fix crash while aborting hibernation (Re:[linux-pm] [regression] "drm/i915: implement new pm ops" disables irq onaborted s2disk)

[Alan Jenkins]

Rafael J. Wysocki wrote:
> On Thursday 04 February 2010, Zhenyu Wang wrote:
>   
> > On 2010.02.03 23:44:41 +0100, Rafael J. Wysocki wrote:
> >     
> > > On Wednesday 03 February 2010, Alan Jenkins wrote:
> > >       
> > > > Hi
> > > >
> > > > I found this regression on my EeePC 701 with modesetting enabled.  When 
> > > > I hibernate using s2disk, I can abort the hibernation by pressing the 
> > > > backspace key.  Doing so breaks X on 2.6.32-rc6 (but not 2.6.32).
> > > >         
> > > Yeah.
> > >
> > > To be honest, I knew that's going to happen, but didn't have the time to take
> > > care of it.
> > >
> > > The problem is that i915 does literally _nothing_ in its .thaw() callback,
> > > although it should at least reverse whatever .freeze() did to the hardware
> > > (and memory allocations and so on), so that the adapter is functional
> > > after creating the image.
> > >
> > > Fixing this requires some thought, though, because at the moment .freeze()
> > > thinks it's .suspend(), which is not the case as this report clearly shows.
> > > So, in fact i915_pci_suspend() has to be split into the .freeze() part and
> > > the poweroff part cleanly and that's not  so simple (at least to me).
> > >
> > >       
> > Right, I think that'll be more clean, stuff in i915_save/restore_state() need
> > to be splited too, especially isolate stuff for mode setting and other device
> > state, as what my original purpose for this is to remove extra mode setting 
> > cycle in old behavior so not waste time for hibernate.
> >     
>
> We can't really do that, because we'll need to restore the saved state at the
> resume-from-hibernation stage.
>
> The appended patch fixes the issue for me, although it's been only tested
> a little.  It sort of defeats the purpose of commit
> cbda12d77ea590082edb6d30bd342a67ebc459e0, but I don't see any less invasive
> way to fix this except maybe for reverting that commit entirely.
>
> Note that the drm_irq_[un]install() thing may be unnecessary, but I wasn't sure
> about that and surely wouldn't suggest doing that for 2.6.33.  Also it looks like
> some things from the freeze and thaw parts may be moved to the "low-level"
> suspend and resume parts, respectively, but that would require some
> i915_gem_* surgery I was too scared to do.
>
> Alan, please test, i915 guys, please review.
>
> Rafael
>   

The patch works very nicely on my eeepc.

Thanks
(and thanks again for all your hard work this cycle, and specifically 
for pointing me to the s2disk hang-fix)

Alan
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