[Intel-gfx] [PATCH] drm/i915: Add Baytrail PSR Support.

[Chris Wilson]

On Wed, Jan 29, 2014 at 11:54:00AM -0200, Rodrigo Vivi wrote:
> On Wed, Jan 29, 2014 at 11:27 AM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > On Wed, Jan 29, 2014 at 11:24:44AM -0200, Rodrigo Vivi wrote:
> >> On Wed, Jan 29, 2014 at 11:12 AM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> >> > On Wed, Jan 29, 2014 at 10:47:54AM -0200, Rodrigo Vivi wrote:
> >> >> This patch adds PSR Support to Baytrail.
> >> >>
> >> >> Baytrail cannot easily detect screen updates and force PSR exit.
> >> >> So we inactivate it on {busy_ioctl, set_domain, sw_finish and mark_busy
> >> >> and update to enable it back on next display mark_idle.
> >> >>
> >> >> v2: Also inactivate PSR on cursor update.
> >> >> v3: Inactivate PSR on mark_busy, dset_domain and sw_finish_ioctl, and
> >> >>     early on page flip besides avoid initializing inactive/active flag
> >> >>     more than once.
> >> >> v4: Fix identation issues.
> >> >> v5: Rebase and add Baytrail per pipe support although leaving PIPE_B
> >> >>     support disabled by for now since it isn't working properly yet.
> >> >> v6: Removing forgotten comment and useless clkgating definition.
> >> >
> >> > Not set-domain. This is semantically a flush and so should be after the
> >> > damage is done.
> >>
> >> Yep, I semantically I agree, but if we let to inactivate psr after
> >> damage is done we will miss screen updates.
> >> This was the safest way to get psr enabled and fully working and
> >> passing crc tests.
> >> If you have another place to suggest i'd be glad in do some tests
> >> here, but for now this is the more stable place I know about.
> >
> > It's the test that are at fault here for not following the established
> > ABI imo.
> 
> this makes sense.
> 
> do we have this established ABI documented somewhere?

Only what was established as required to make things work a few years
ago...
 
> and what is missing on test? is it a busy ioctl in the end?

busy or even a sw_finish. I see it already did the sw_finish. We have in
the past talked about formalizing the gap in the documentation with a
new call...
 
> but anyway, doing this on set_domain we could fix the psr on
> environments that doesn't follow this abi like KDE.

As we have discussed in the past, that is an issue in the ddx that
short-circuits the required flush if there was only GTT damage.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre