Re: [PATCH v2] drm/i915: move power domain init earlier during system resume

[Imre Deak <imre.deak@intel.com>]

On Tue, 2014-04-01 at 19:48 +0200, Daniel Vetter wrote:
> On Tue, Apr 01, 2014 at 07:55:22PM +0300, Imre Deak wrote:
> > During resume the intel hda audio driver depends on the i915 driver
> > reinitializing the audio power domain. Since the order of calling the
> > i915 resume handler wrt. that of the audio driver is not guaranteed,
> > move the power domain reinitialization step to the resume_early
> > handler. This is guaranteed to run before the resume handler of any
> > other driver.
> > 
> > The power domain initialization in turn requires us to enable the i915
> > pci device first, so move that part earlier too.
> > 
> > Accordingly disabling of the i915 pci device should happen after the
> > audio suspend handler ran. So move the disabling later from the i915
> > resume handler to the resume_late handler.
> > 
> > v2:
> > - move intel_uncore_sanitize/early_sanitize earlier too, so they don't
> >   get reordered wrt. intel_power_domains_init_hw()
> > 
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76152
> > Signed-off-by: Imre Deak <imre.deak@intel.com>
> 
> So this is kinda why we should have gone with something proper, like a new
> hdmi sink platform device created by i915 and registered as a driver by
> snd-hda. Then the power domains stuff in the device core should take care
> of these kinds of ordering issues. Or at least snd-hda can tell it that it
> needs to wait for the hdmi-sink power domain to go on first before it can
> resume, I'm not really fluent on the details here.
> 
> And having a hdmi sink bus would allow us to throw all kinds of crap into
> a clearly-defined interface, e.g. eld handling, hdcp synchronization, hpd
> forwarding and all the other fun stuff.
> 
> So not sure what I should do with this here now.

Right, I'm not too happy about this solution either, so if anything it
could be considered only a stop-gap fix. What you suggest seems to be a
cleaner way but it'd require more time to investigate/implement at least
on my part (but I'm ok to put it on my TODO list).

--Imre