Re: [PATCH] drm/i915: apply the PCI_D0/D3 hibernation workaround everywhere on pre GEN6

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Jul 01, 2015 at 11:51:27AM +0200, Pavel Machek wrote:
> > > > - Embedded panels have a well defined shutdown sequence. We
>         don't
> 
> > > >   have
> > > >   any good reason to not follow this, in fact for some panels the
> > > >   subsequent reinitialization could be problematic in case of a hard
> > > >   power-off. (Thanks to Jani for this info)
> > > 
> > > Please cite concrete example. I have yet to see machine that would not
> > > power up on forced power down. In fact, I argue that such machine
> > > would be very broken, and that such machine does not exist. While we
> > > have these real machines broken:
> > > 
> > > > +	 * Lenovo Thinkpad X301, X61s, X60, T60, X41
> > > > +	 * Fujitsu FSC S7110
> > > > +	 * Acer Aspire 1830T
> > > 
> > > What makes you think that BIOS writers will do something different for
> > > Gen6+ hardware? X301 is not that old.
> > 
> > Thinkpad X1 Carbon (IVB) is perfectly happy with the D3, so clearly
> > something changed for Lenovo at least. And most machines (old and new)
> > have no problems whatsoever with the D3.
> 
>  Well, one machine being happy does not matter that much...

I said most machines, not one.

> as going to
> D3 has no real benefits.

Sure it does. Eventually we'll want to avoid resuming runtime suspended
devices when entering system suspend. For broken machines we'd need to
resume the GPU at that point.

> 
> > It might be interesting to see if hibernate even works in Windows
> > without some vendor driver on these machines.
> 
> I don't have windows nearby..

Me neither.

-- 
Ville Syrj�l�
Intel OTC