[Intel-gfx] [PATCH 1/4] drm/i915: Increase PSR Idle Frame to 2.

[Daniel Vetter]

On Thu, Sep 04, 2014 at 01:18:19PM +0300, Ville Syrjälä wrote:
> On Thu, Sep 04, 2014 at 01:04:27PM +0300, Ville Syrjälä wrote:
> > On Thu, Sep 04, 2014 at 11:29:16AM +0200, Daniel Vetter wrote:
> > > On Thu, Sep 04, 2014 at 10:55:16AM +0300, Ville Syrjälä wrote:
> > > > On Wed, Sep 03, 2014 at 10:49:56PM -0400, Rodrigo Vivi wrote:
> > > > > With Software tracking we are going to PSR sooner than we should and staying
> > > > > with blank screens in many cases.
> > > > > 
> > > > > Using 2 identical frames to detect idleness is safier.
> > > > 
> > > > This idle frame detection still depends of FBC right?
> > > > 
> > > > I believe if we want to go for full sw tracking on HSW/BDW we need to
> > > > use the debug register to force PSR entry/exit.
> > > 
> > > Currently the sw tracking relies upon 1 additional full upload happening
> > > after the flush, which hopefully should magically happen if we have just 1
> > > idle frame.
> > > 
> > > If we'd completely switch to sw tracking we'd need to set up a vblank
> > > worker to disable psr after the next vblank, which would comlicate the
> > > code I think.
> > 
> > vlv/chv have no hw tracking so if the current sw tracking can't deal
> > with that then it would seem to need more work.
> 
> Hmm. Actually they seem to have a hw timer mode where we can program the
> number of idle frames. I think idle here means "since the last plane
> register frobbing" as there's no real modification tracking ala. FBC.
> So maybe it can work roughly the same way as HSW in that regard.

Essentially the primitive the current code needs (modulo bugs, which seem
to still be) is to "upload one more full frame, then enter psr". If a lot
of platforms can't do that themselves I guess we could wrap some helpers
for them.

But if there's some real sw tracking bug still, and Rodrigo's patch looks
like this is still the case, we need to fix that ofc.
-Daniel

> 
> > 
> > > -Daniel
> > > 
> > > > 
> > > > > 
> > > > > Discovered and validated with refactored igt/kms_sink_psr_crc.
> > > > > 
> > > > > Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> > > > > ---
> > > > >  drivers/gpu/drm/i915/intel_dp.c | 2 +-
> > > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > > 
> > > > > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > > > > index f79473b..a796831 100644
> > > > > --- a/drivers/gpu/drm/i915/intel_dp.c
> > > > > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > > > > @@ -1813,7 +1813,7 @@ static void intel_edp_psr_enable_source(struct intel_dp *intel_dp)
> > > > >  	struct drm_device *dev = dig_port->base.base.dev;
> > > > >  	struct drm_i915_private *dev_priv = dev->dev_private;
> > > > >  	uint32_t max_sleep_time = 0x1f;
> > > > > -	uint32_t idle_frames = 1;
> > > > > +	uint32_t idle_frames = 2;
> > > > >  	uint32_t val = 0x0;
> > > > >  	const uint32_t link_entry_time = EDP_PSR_MIN_LINK_ENTRY_TIME_8_LINES;
> > > > >  	bool only_standby = false;
> > > > > -- 
> > > > > 1.9.3
> > > > > 
> > > > > _______________________________________________
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> > > > > Intel-gfx at lists.freedesktop.org
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> > > > 
> > > > -- 
> > > > Ville Syrjälä
> > > > Intel OTC
> > > > _______________________________________________
> > > > Intel-gfx mailing list
> > > > Intel-gfx at lists.freedesktop.org
> > > > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> > > 
> > > -- 
> > > Daniel Vetter
> > > Software Engineer, Intel Corporation
> > > +41 (0) 79 365 57 48 - http://blog.ffwll.ch
> > 
> > -- 
> > Ville Syrjälä
> > Intel OTC
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Ville Syrjälä
> Intel OTC

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch