Re: [PATCH v2 4/4] drm/i915: Calculate vlv/chv intermediate watermarks correctly, v2.

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

On Thu, May 04, 2017 at 10:12:52AM +0200, Maarten Lankhorst wrote:
> Op 03-05-17 om 20:03 schreef Ville Syrjälä:
> > On Wed, May 03, 2017 at 06:18:46PM +0200, Maarten Lankhorst wrote:
> >> Op 03-05-17 om 18:07 schreef Ville Syrjälä:
> >>> On Wed, May 03, 2017 at 05:53:34PM +0200, Maarten Lankhorst wrote:
> >>>> Op 03-05-17 om 16:11 schreef Ville Syrjälä:
> >>>>> On Wed, May 03, 2017 at 04:06:37PM +0200, Maarten Lankhorst wrote:
> >>>>>> Op 03-05-17 om 15:45 schreef Ville Syrjälä:
> >>>>>>> On Mon, May 01, 2017 at 03:34:34PM +0200, Maarten Lankhorst wrote:
> >>>>>>>> The watermarks it should calculate against are the old optimal watermarks.
> >>>>>>>> The currently active crtc watermarks are pure fiction, and are invalid in
> >>>>>>>> case of a nonblocking modeset, page flip enabling/disabling planes or any
> >>>>>>>> other reason.
> >>>>>>>>
> >>>>>>>> When the crtc is disabled or during a modeset the intermediate watermarks
> >>>>>>>> don't need to be programmed separately, and could be directly assigned
> >>>>>>>> to the optimal watermarks.
> >>>>>>>>
> >>>>>>>> Also rename crtc_state to new_crtc_state, to distinguish it from the old state.
> >>>>>>>>
> >>>>>>>> Changes since v1:
> >>>>>>>> - Use intel_atomic_get_old_crtc_state. (ville)
> >>>>>>>>
> >>>>>>>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> >>>>>>>> ---
> >>>>>>>>  drivers/gpu/drm/i915/intel_pm.c | 20 ++++++++++++++------
> >>>>>>>>  1 file changed, 14 insertions(+), 6 deletions(-)
> >>>>>>>>
> >>>>>>>> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> >>>>>>>> index 0f344b1fff45..a09396ee1f3d 100644
> >>>>>>>> --- a/drivers/gpu/drm/i915/intel_pm.c
> >>>>>>>> +++ b/drivers/gpu/drm/i915/intel_pm.c
> >>>>>>>> @@ -1458,16 +1458,24 @@ static void vlv_atomic_update_fifo(struct intel_atomic_state *state,
> >>>>>>>>  
> >>>>>>>>  static int vlv_compute_intermediate_wm(struct drm_device *dev,
> >>>>>>>>  				       struct intel_crtc *crtc,
> >>>>>>>> -				       struct intel_crtc_state *crtc_state)
> >>>>>>>> +				       struct intel_crtc_state *new_crtc_state)
> >>>>>>>>  {
> >>>>>>>> -	struct vlv_wm_state *intermediate = &crtc_state->wm.vlv.intermediate;
> >>>>>>>> -	const struct vlv_wm_state *optimal = &crtc_state->wm.vlv.optimal;
> >>>>>>>> -	const struct vlv_wm_state *active = &crtc->wm.active.vlv;
> >>>>>>>> +	struct vlv_wm_state *intermediate = &new_crtc_state->wm.vlv.intermediate;
> >>>>>>>> +	const struct vlv_wm_state *optimal = &new_crtc_state->wm.vlv.optimal;
> >>>>>>>> +	const struct intel_crtc_state *old_crtc_state =
> >>>>>>>> +		intel_atomic_get_old_crtc_state(new_crtc_state->base.state, crtc);
> >>>>>>>> +	const struct vlv_wm_state *active = &old_crtc_state->wm.vlv.optimal;
> >>>>>>>>  	int level;
> >>>>>>>>  
> >>>>>>>> +	if (!new_crtc_state->base.active || drm_atomic_crtc_needs_modeset(&new_crtc_state->base)) {
> >>>>>>>> +		*intermediate = *optimal;
> >>>>>>>> +
> >>>>>>>> +		return 0;
> >>>>>>>> +	}
> >>>>>>>> +
> >>>>>>>>  	intermediate->num_levels = min(optimal->num_levels, active->num_levels);
> >>>>>>>>  	intermediate->cxsr = optimal->cxsr && active->cxsr &&
> >>>>>>>> -		!crtc_state->disable_cxsr;
> >>>>>>>> +		!new_crtc_state->disable_cxsr;
> >>>>>>> We need to consider disable_cxsr even in the modeset case.
> >>>>>> Why is this? crtc_state->disable_cxsr is set if any plane is part of the crtc during modeset, so it's disabled during modeset already.
> >>>>> It's set if any plane is enabling/disabling, which should be quite
> >>>>> typical during a modeset.
> >>>> Yeah but .initial_watermarks is called during crtc_enable, so cxsr will get enabled anyway.
> >>> Which is not what we want. CxSR must stay off until the planes have been
> >>> enabled.
> >>>
> >> In that case why is it enabled in .initial_watermarks at all? It should be in optimize_watermarks then..
> > Because we can keep it enabled across the update unless planes are
> > getting enabled or disabled.
> >
> So for the modeset case, computing intermediate watermarks:
> 
> *intermediate = *optimal;
> if (needs_modeset)
> 	intermediate->cxsr = false;
> 
> if (optimal->cxsr && !intermediate->cxsr)
> 	new_crtc_state->wm.need_postvbl_update = true;
> 
> ?


Or maybe

	if (blah) {
		*intermediate = *optimal;
		goto out;
	}

	// min/max stuff

out:
	if (disable_cxsr)
		intermediate->cxsr = false;
	if (memcmp(...


-- 
Ville Syrjälä
Intel OTC
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