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

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

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.

-- 
Ville Syrjälä
Intel OTC
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