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

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 26 Jul 2024, Nemesa Garg <nemesa.garg@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.

>
> Signed-off-by: Nemesa Garg <nemesa.garg@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