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 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.

-- 
Ville Syrjälä
Intel OTC
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