Re: [PATCH 18/20] drm/i915: YCBCR 420 support for LSPCON

["Sharma, Shashank" <shashank.sharma@xxxxxxxxx>]

Regards

Shashank


On 7/12/2017 10:45 PM, Ville Syrjälä wrote:
> On Mon, Jul 10, 2017 at 04:48:46PM +0530, Shashank Sharma wrote:
> > LSPCON chips support YCBCR420 outputs. To be able to get
> > YCBCR420 output from LSPCON chip, the source should:
> > - Generate YCBCR444 HDMI output
> > - Set AVI infoframes for a YCBCR420 output.
> >
> > LSPCON FW gets the information from AVI infoframes, and generates
> > YCBCR420 output from a YCBCR444 input. This patch adds the necessary
> > changes to drive YCBCR420 output from LSPCON based HDMI output.
> >
> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > Cc: Imre Deak <imre.deak@xxxxxxxxx>
> > Signed-off-by: Shashank Sharma <shashank.sharma@xxxxxxxxx>
> > ---
> >   drivers/gpu/drm/i915/intel_display.c | 10 +++++++---
> >   drivers/gpu/drm/i915/intel_dp.c      | 16 +++++++++++++++-
> >   drivers/gpu/drm/i915/intel_drv.h     | 20 +++++++++++++++++---
> >   drivers/gpu/drm/i915/intel_hdmi.c    |  7 +++++--
> >   drivers/gpu/drm/i915/intel_lspcon.c  | 17 +++++++++++++++++
> >   5 files changed, 61 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index c5ff568..c3c7b31 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -8125,9 +8125,11 @@ static void haswell_set_pipemisc(struct drm_crtc *crtc)
> >   			val |= PIPEMISC_DITHER_ENABLE | PIPEMISC_DITHER_TYPE_SP;
> >   
> >   		if (config->ycbcr420) {
> > -			val |= PIPEMISC_OUTPUT_YCBCR |
> > -				PIPEMISC_YCBCR420_ENABLE |
> > -				PIPEMISC_YCBCR420_MODE_BLEND;
> > +			val |= PIPEMISC_OUTPUT_YCBCR;
> > +
> > +			if (!config->lspcon_active)
> > +				val |= PIPEMISC_YCBCR420_ENABLE |
> > +					PIPEMISC_YCBCR420_MODE_BLEND;
> >   		}
> >   
> >   		I915_WRITE(PIPEMISC(intel_crtc->pipe), val);
> > @@ -14205,11 +14207,13 @@ static void intel_setup_outputs(struct drm_i915_private *dev_priv)
> >   		 * DDI_BUF_CTL_A or SFUSE_STRAP registers, find another way to
> >   		 * detect the ports.
> >   		 */
> > +
> >   		intel_ddi_init(dev_priv, PORT_A);
> >   		intel_ddi_init(dev_priv, PORT_B);
> >   		intel_ddi_init(dev_priv, PORT_C);
> >   
> >   		intel_dsi_init(dev_priv);
> > +
> >   	} else if (HAS_DDI(dev_priv)) {
> >   		int found;
> >   
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > index 67bc8a7a..1690aa9 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -1614,7 +1614,9 @@ intel_dp_compute_config(struct intel_encoder *encoder,
> >   	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> >   	struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
> >   	struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
> > -	enum port port = dp_to_dig_port(intel_dp)->port;
> > +	struct intel_digital_port *dig_port = enc_to_dig_port(&encoder->base);
> > +	enum port port = dig_port->port;
> > +	struct intel_lspcon *lspcon = &dig_port->lspcon;
> >   	struct intel_crtc *intel_crtc = to_intel_crtc(pipe_config->base.crtc);
> >   	struct intel_connector *intel_connector = intel_dp->attached_connector;
> >   	struct intel_digital_connector_state *intel_conn_state =
> > @@ -1635,6 +1637,18 @@ intel_dp_compute_config(struct intel_encoder *encoder,
> >   	common_len = intel_dp_common_len_rate_limit(intel_dp,
> >   						    intel_dp->max_link_rate);
> >   
> > +	/* LSPCON needs special handling to drive YCBCR420 outputs */
> > +	if (lspcon->active) {
> > +		struct drm_connector *connector = &intel_connector->base;
> > +		int clock_8bpc = pipe_config->base.adjusted_mode.crtc_clock;
> > +		int clock_12bpc = clock_8bpc * 3 / 2;
> > +
> > +		pipe_config->lspcon_active = true;
> > +		pipe_config->ycbcr420 = lspcon_ycbcr420_config(connector,
> > +					     pipe_config, &clock_12bpc,
> > +					     &clock_8bpc);
> All this clock stuff here seems pointless. So I'd just replace this
> stuff with the straightforward 'pipe_config->ycbcr420 = mode_needs_420';
pipe_config->ycbcr_420 = true means we have committed into state that we 
can support this mode in YCBCR420.
But for that, we need to check connector->ycbcr420_allowed too.
Also, when the mode is 420, we need to half the clock_8bpc and clock_12bpc.

This whole stuff is happening into lspcon_ycbcr420_config function 
(which internally re-use hdmi_ycncr420_config from HDMI 2.0 series).
That's why the call is important.
> > +	}
> > +
> >   	/* No common link rates between source and sink */
> >   	WARN_ON(common_len <= 0);
> >   
> > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> > index ed04de9..40d56f2 100644
> > --- a/drivers/gpu/drm/i915/intel_drv.h
> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > @@ -790,6 +790,9 @@ struct intel_crtc_state {
> >   
> >   	/* HDMI output type */
> >   	bool ycbcr420;
> > +
> > +	/* LSPCON is active on port */
> > +	bool lspcon_active;
> >   };
> >   
> >   struct intel_crtc {
> > @@ -1205,6 +1208,12 @@ static inline struct intel_dp *enc_to_intel_dp(struct drm_encoder *encoder)
> >   	return &enc_to_dig_port(encoder)->dp;
> >   }
> >   
> > +static inline struct intel_lspcon *
> > +enc_to_intel_lspcon(struct drm_encoder *encoder)
> > +{
> > +	return &enc_to_dig_port(encoder)->lspcon;
> > +}
> > +
> >   static inline struct intel_digital_port *
> >   dp_to_dig_port(struct intel_dp *intel_dp)
> >   {
> > @@ -1675,14 +1684,16 @@ void intel_hdmi_init_connector(struct intel_digital_port *intel_dig_port,
> >   			       struct intel_connector *intel_connector);
> >   struct intel_hdmi *enc_to_intel_hdmi(struct drm_encoder *encoder);
> >   bool intel_hdmi_compute_config(struct intel_encoder *encoder,
> > -			       struct intel_crtc_state *pipe_config,
> > -			       struct drm_connector_state *conn_state);
> > +				struct intel_crtc_state *pipe_config,
> > +				struct drm_connector_state *conn_state);
> >   void intel_hdmi_handle_sink_scrambling(struct intel_encoder *intel_encoder,
> >   				       struct drm_connector *connector,
> >   				       bool high_tmds_clock_ratio,
> >   				       bool scrambling);
> >   void intel_dp_dual_mode_set_tmds_output(struct intel_hdmi *hdmi, bool enable);
> > -
> > +bool intel_hdmi_ycbcr420_config(struct drm_connector *connector,
> > +				struct intel_crtc_state *config,
> > +				int *clock_12bpc, int *clock_8bpc);
> >   
> >   /* intel_lvds.c */
> >   void intel_lvds_init(struct drm_i915_private *dev_priv);
> > @@ -2003,6 +2014,9 @@ void intel_color_load_luts(struct drm_crtc_state *crtc_state);
> >   bool lspcon_init(struct intel_digital_port *intel_dig_port);
> >   void lspcon_resume(struct intel_lspcon *lspcon);
> >   void lspcon_wait_pcon_mode(struct intel_lspcon *lspcon);
> > +bool lspcon_ycbcr420_config(struct drm_connector *connector,
> > +			    struct intel_crtc_state *config,
> > +			    int *clock_12bpc, int *clock_8bpc);
> >   
> >   /* intel_pipe_crc.c */
> >   int intel_pipe_crc_create(struct drm_minor *minor);
> > diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> > index d1b1efc..a08ab99 100644
> > --- a/drivers/gpu/drm/i915/intel_hdmi.c
> > +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> > @@ -1362,8 +1362,7 @@ static bool hdmi_12bpc_possible(struct intel_crtc_state *crtc_state,
> >   	return true;
> >   }
> >   
> > -static bool
> > -intel_hdmi_ycbcr420_config(struct drm_connector *connector,
> > +bool intel_hdmi_ycbcr420_config(struct drm_connector *connector,
> >   			       struct intel_crtc_state *config,
> >   			       int *clock_12bpc, int *clock_8bpc)
> >   {
> > @@ -1380,6 +1379,10 @@ intel_hdmi_ycbcr420_config(struct drm_connector *connector,
> >   	*clock_8bpc /= 2;
> >   	config->ycbcr420 = true;
> >   
> > +	/* LSPCON doesn't need scaler for YCBCR420 output */
> > +	if (config->lspcon_active)
> > +		return true;
> > +
> >   	/* YCBCR 420 output conversion needs a scaler */
> >   	if (skl_update_scaler_crtc_420_output(config)) {
> >   		DRM_ERROR("Scaler allocation for output failed\n");
> > diff --git a/drivers/gpu/drm/i915/intel_lspcon.c b/drivers/gpu/drm/i915/intel_lspcon.c
> > index a350d79..f611b6d 100644
> > --- a/drivers/gpu/drm/i915/intel_lspcon.c
> > +++ b/drivers/gpu/drm/i915/intel_lspcon.c
> > @@ -202,6 +202,21 @@ static void lspcon_resume_in_pcon_wa(struct intel_lspcon *lspcon)
> >   	DRM_DEBUG_KMS("LSPCON DP descriptor mismatch after resume\n");
> >   }
> >   
> > +bool lspcon_ycbcr420_config(struct drm_connector *connector,
> > +			    struct intel_crtc_state *config,
> > +			    int *clock_12bpc, int *clock_8bpc)
> > +{
> > +	struct drm_display_info *info = &connector->display_info;
> > +	struct drm_display_mode *mode = &config->base.adjusted_mode;
> > +
> > +	if (drm_mode_is_420_only(info, mode)) {
> > +		return intel_hdmi_ycbcr420_config(connector, config,
> > +					  clock_12bpc, clock_8bpc);
> > +	}
> > +
> > +	return false;
> > +}
> > +
> >   void lspcon_resume(struct intel_lspcon *lspcon)
> >   {
> >   	enum drm_lspcon_mode expected_mode;
> > @@ -233,6 +248,7 @@ bool lspcon_init(struct intel_digital_port *intel_dig_port)
> >   	struct intel_lspcon *lspcon = &intel_dig_port->lspcon;
> >   	struct drm_device *dev = intel_dig_port->base.base.dev;
> >   	struct drm_i915_private *dev_priv = to_i915(dev);
> > +	struct drm_connector *connector = &dp->attached_connector->base;
> >   
> >   	if (!IS_GEN9(dev_priv)) {
> >   		DRM_ERROR("LSPCON is supported on GEN9 only\n");
> > @@ -264,6 +280,7 @@ bool lspcon_init(struct intel_digital_port *intel_dig_port)
> >   		return false;
> >   	}
> >   
> > +	connector->ycbcr_420_allowed = true;
> >   	drm_dp_read_desc(&dp->aux, &dp->desc, drm_dp_is_branch(dp->dpcd));
> >   
> >   	DRM_DEBUG_KMS("Success: LSPCON init\n");
> > --
> > 2.7.4

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