[Intel-gfx] [PATCH 2/5] drm/i915: PSR: Remove Low Power HW tracking mask.

[Rodrigo Vivi]

On Mon, Jun 22, 2015 at 3:31 PM Runyan, Arthur J <arthur.j.runyan at intel.com>
wrote:

> -- Daniel
> >> I guess I don't really understand your description, but it does sound
> >> strange ... runtime pm enabling from my patch is only about D3, power
> >> well changes are still done. And as long as we have anything enabled
> >> (even with PSR) we'll prevent D3.
> >>
> >> So the only thing I can think of is that somehow D3 wreaks something
> >> in the PSR setup and that's causing issues. Unfortunately I have no
> >> idea about our hw details around PSR and D3, so no idea. Maybe Art has
> >> some?
> >
> -- Rodrigo
> >I don't know this relation as well. When I found this LPSP maks that
> >made PSR working it was totally by forcing all masks and start
> >removing one by one up to the point that this Low Power something did
> >the trick. At that time Artur had told about power well handling
> >enabled, but now after Mathew reported that issue I noticed this Low
> >power flag was also related to runtime PM...
> >
>
> Let me see if I understand what is happening.  Runtime PM seemed to cause
> PSR to miss some screen updates when you had LPSP masked, then you stopped
> masking  LPSP and it fixed the missing updates?
>

Yes.


> My first guess is that you are not in LPSP at this point, so removing the
> mask is effectively disabling PSR, which prevents PSR from missing screen
> updates.   Are you still getting good PSR residency with LPSP masked in
> this situation?
>

Without LPSP masked residency is 0 until I enable runtime_pm from i915 and
audio. But once they get enabled residency counter increases fast.

Also if I have wireless searching for network or trying to connect
residency stay 0, but once connection gets stablished or stop trying to
connect than PSR residency start increasing again.


>
> The LPSP mask is only there fro debug.  We don't normally want PSR to
> enter without LPSP because there can be undesirable things like clocks
> stopping which could break the display audio controller and codec.
>

Yeah, I know. I just masked because I could never get PSR count bigger than
0 without this mask previously...
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