[PATCH 2/2] drm/i915/display: Call panel_fitting from pipe_config

[Garg, Nemesa]

> -----Original Message-----
> From: Jani Nikula <jani.nikula at linux.intel.com>
> Sent: Tuesday, July 30, 2024 1:27 PM
> To: Garg, Nemesa <nemesa.garg at intel.com>; intel-gfx at lists.freedesktop.org
> Cc: Garg, Nemesa <nemesa.garg at intel.com>
> Subject: Re: [PATCH 2/2] drm/i915/display: Call panel_fitting from pipe_config
> 
> On Fri, 26 Jul 2024, Nemesa Garg <nemesa.garg at intel.com> wrote:
> > In panel fitter/pipe scaler scenario the pch_pfit configuration
> > currently takes place before accounting for pipe_src width for joiner.
> > This causes issue when pch_pfit and joiner gets enabled together.
> >
> > Introduce a new boolean flag is_required which can be filled during dp
> > compute_config and later is used to compute panel_fitting in
> > pipe_config. Modify pch_panel_fitting to handle joiner pipes by
> > adjusting crtc_hdisplay accordingly.
> 
> Superficially looks simple enough, but this actually adds a bunch of complexity.
> It's not obvious why encoders handle panel fitting in completely different places,
> or what "pch_pfit.is_required" really means.
> 
> BR,
> Jani.
> 
Hi Jani,

In joiner cases we need to do panel fitting calculations after the calculated pipe src width.

So one solution I thought of is as mentioned below:
For each encoder first panel_compute_config is called and then intel_panel_fitting.
So to simplify this I am replacing the  intel_panel_fitting  with the flag and then calling it at one place in pipe_config.
As done in trybot patch https://patchwork.freedesktop.org/series/136483/.

Other solution can be let the flow for panel_fitting is same for non-joiner case for edp/dp and if joiner
is enabled call panel_fitting again in later stage ie after pipe_config.

Please suggest what can be the better solution.

Thanks and Regards,
Nemesa
> >
> > Signed-off-by: Nemesa Garg <nemesa.garg at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_display.c       | 11 +++++++++++
> >  drivers/gpu/drm/i915/display/intel_display_types.h |  1 +
> >  drivers/gpu/drm/i915/display/intel_dp.c            |  7 ++-----
> >  drivers/gpu/drm/i915/display/intel_panel.c         |  3 +++
> >  4 files changed, 17 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> > b/drivers/gpu/drm/i915/display/intel_display.c
> > index 8bbde03f2508..a7194a84b6b8 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -4796,6 +4796,17 @@ intel_modeset_pipe_config(struct
> intel_atomic_state *state,
> >  		return ret;
> >  	}
> >
> > +	for_each_new_connector_in_state(&state->base, connector,
> connector_state, i) {
> > +		if (connector_state->crtc != &crtc->base)
> > +			continue;
> > +
> > +		if (crtc_state->pch_pfit.is_required) {
> > +			ret = intel_panel_fitting(crtc_state, connector_state);
> > +			if (ret)
> > +				return ret;
> > +		}
> > +	}
> > +
> >  	/* Dithering seems to not pass-through bits correctly when it should, so
> >  	 * only enable it on 6bpc panels and when its not a compliance
> >  	 * test requesting 6bpc video pattern.
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h
> > b/drivers/gpu/drm/i915/display/intel_display_types.h
> > index a04d52dbf6e1..a4ab26d8fa43 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > @@ -1258,6 +1258,7 @@ struct intel_crtc_state {
> >  		struct drm_rect dst;
> >  		bool enabled;
> >  		bool force_thru;
> > +		bool is_required;
> >  	} pch_pfit;
> >
> >  	/* FDI configuration, only valid if has_pch_encoder is set. */ diff
> > --git a/drivers/gpu/drm/i915/display/intel_dp.c
> > b/drivers/gpu/drm/i915/display/intel_dp.c
> > index d0d878da71ee..d892c5a429f1 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -2922,11 +2922,8 @@ intel_dp_compute_config(struct intel_encoder
> *encoder,
> >  		pipe_config->has_pch_encoder = true;
> >
> >  	fixed_mode = intel_panel_fixed_mode(connector, adjusted_mode);
> > -	if (intel_dp_is_edp(intel_dp) && fixed_mode) {
> > -		ret = intel_panel_compute_config(connector, adjusted_mode);
> > -		if (ret)
> > -			return ret;
> > -	}
> > +	if (intel_dp_is_edp(intel_dp) && fixed_mode)
> > +		pipe_config->pch_pfit.is_required = true;
> >
> >  	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
> >  		return -EINVAL;
> > diff --git a/drivers/gpu/drm/i915/display/intel_panel.c
> > b/drivers/gpu/drm/i915/display/intel_panel.c
> > index dd18136d1c61..0da45c2330d3 100644
> > --- a/drivers/gpu/drm/i915/display/intel_panel.c
> > +++ b/drivers/gpu/drm/i915/display/intel_panel.c
> > @@ -395,6 +395,9 @@ static int pch_panel_fitting(struct intel_crtc_state
> *crtc_state,
> >  	u16 crtc_hdisplay = adjusted_mode->crtc_hdisplay;
> >  	u16 crtc_vdisplay = adjusted_mode->crtc_vdisplay;
> >
> > +	if (crtc_state->joiner_pipes)
> > +		crtc_hdisplay = adjusted_mode->crtc_hdisplay / 2;
> > +
> >  	/* Native modes don't need fitting */
> >  	if (crtc_hdisplay == pipe_src_w &&
> >  	    crtc_vdisplay == pipe_src_h &&
> 
> --
> Jani Nikula, Intel