Re: [PATCH v2] drm/i915/tgl: Implement TGL DisplayPort training sequence

[Manasi Navare <manasi.d.navare@intel.com>]

On Tue, Aug 20, 2019 at 03:01:38PM -0700, José Roberto de Souza wrote:
> On TGL some registers moved from DDI to transcoder and the
> DisplayPort training sequence has a separate BSpec page.
> 
> I started adding 'ifs' to the original intel_ddi_pre_enable_dp() but
> it was becoming really hard to follow, so a new and cleaner function
> for TGL was added with comments of all steps. It's similar to ICL, but
> different enough to deserve a new function
> 
> The rest of DisplayPort enable and the whole disable sequences
> remained the same.
> 
> v2: FEC and DSC should be enabled on sink side before start link
> training(Maarten reported and Manasi confirmed the DSC part)
> 
> BSpec: 49190
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Manasi Navare <manasi.d.navare@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
> Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_ddi.c | 138 ++++++++++++++++++++++-
>  drivers/gpu/drm/i915/display/intel_dp.c  |   8 +-
>  2 files changed, 138 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index 8eb2b3ec01ed..1c1534e2d833 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -1761,7 +1761,14 @@ void intel_ddi_set_vc_payload_alloc(const struct intel_crtc_state *crtc_state,
>  	I915_WRITE(TRANS_DDI_FUNC_CTL(cpu_transcoder), temp);
>  }
>  
> -void intel_ddi_enable_transcoder_func(const struct intel_crtc_state *crtc_state)
> +/*
> + * Returns the TRANS_DDI_FUNC_CTL value based on CRTC state.
> + *
> + * Only intended to be used by intel_ddi_enable_transcoder_func() and
> + * intel_ddi_config_transcoder_func().
> + */
> +static u32
> +intel_ddi_transcoder_func_reg_val_get(const struct intel_crtc_state *crtc_state)
>  {
>  	struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
>  	struct intel_encoder *encoder = intel_ddi_get_crtc_encoder(crtc);
> @@ -1845,6 +1852,33 @@ void intel_ddi_enable_transcoder_func(const struct intel_crtc_state *crtc_state)
>  		temp |= DDI_PORT_WIDTH(crtc_state->lane_count);
>  	}
>  
> +	return temp;
> +}
> +
> +void intel_ddi_enable_transcoder_func(const struct intel_crtc_state *crtc_state)
> +{
> +	struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
> +	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> +	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
> +	u32 temp;
> +
> +	temp = intel_ddi_transcoder_func_reg_val_get(crtc_state);
> +	I915_WRITE(TRANS_DDI_FUNC_CTL(cpu_transcoder), temp);
> +}
> +
> +/*
> + * Same as intel_ddi_enable_transcoder_func() but it do not set the enable bit
> + */
> +static void
> +intel_ddi_config_transcoder_func(const struct intel_crtc_state *crtc_state)
> +{
> +	struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
> +	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> +	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
> +	u32 temp;
> +
> +	temp = intel_ddi_transcoder_func_reg_val_get(crtc_state);
> +	temp &= ~TRANS_DDI_FUNC_ENABLE;
>  	I915_WRITE(TRANS_DDI_FUNC_CTL(cpu_transcoder), temp);
>  }
>  
> @@ -3160,9 +3194,93 @@ static void intel_ddi_disable_fec_state(struct intel_encoder *encoder,
>  	POSTING_READ(DP_TP_CTL(port));
>  }
>  
> -static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
> -				    const struct intel_crtc_state *crtc_state,
> -				    const struct drm_connector_state *conn_state)
> +static void tgl_ddi_pre_enable_dp(struct intel_encoder *encoder,
> +				  const struct intel_crtc_state *crtc_state,
> +				  const struct drm_connector_state *conn_state)
> +{
> +	struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
> +	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> +	enum phy phy = intel_port_to_phy(dev_priv, encoder->port);
> +	struct intel_digital_port *dig_port = enc_to_dig_port(&encoder->base);
> +	bool is_mst = intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST);
> +	int level = intel_ddi_dp_level(intel_dp);
> +
> +	intel_dp_set_link_params(intel_dp, crtc_state->port_clock,
> +				 crtc_state->lane_count, is_mst);
> +
> +	/* 1.a got on intel_atomic_commit_tail() */

I think if this comment is kept in the code, better elaborate on what 1 is

> +
> +	/* 2. */
> +	intel_edp_panel_on(intel_dp);
> +
> +	/*
> +	 * 1.b, 3. and 4. is done by before this functions by
> +	 * haswell_crtc_enable()->intel_encoders_pre_pll_enable() and
> +	 * haswell_crtc_enable()->intel_enable_shared_dpll()
> +	 */

Currently there is only gen11_dsi_pre_pll_enable pre_pll_enable hook, is there a 
separate gen12 hook for port clock programming in step 4?

> +
> +	/* 5. */
> +	if (!intel_phy_is_tc(dev_priv, phy) ||
> +	    dig_port->tc_mode != TC_PORT_TBT_ALT)
> +		intel_display_power_get(dev_priv,
> +					dig_port->ddi_io_power_domain);
> +
> +	/* 6. */
> +	icl_program_mg_dp_mode(dig_port);
> +
> +	/*
> +	 * 7.a - Steps in this function that should only be executed over MST
> +	 * master as MST encoders will only be executed on MST master as MST
> +	 * encoder have have it's own pre_enable() hook
> +	 */
> +	intel_ddi_enable_pipe_clock(crtc_state);
> +
> +	/* 7.b */
> +	intel_ddi_config_transcoder_func(crtc_state);
> +
> +	/* 7.d */
> +	icl_disable_phy_clock_gating(dig_port);
> +
> +	/* 7.e */
> +	icl_ddi_vswing_sequence(encoder, crtc_state->port_clock, level,
> +				encoder->type);
> +
> +	/* 7.f */
> +	if (intel_phy_is_combo(dev_priv, phy)) {
> +		bool lane_reversal =
> +			dig_port->saved_port_bits & DDI_BUF_PORT_REVERSAL;
> +
> +		intel_combo_phy_power_up_lanes(dev_priv, phy, false,
> +					       crtc_state->lane_count,
> +					       lane_reversal);
> +	}
> +
> +	/* 7.g */
> +	intel_ddi_init_dp_buf_reg(encoder);
> +
> +	if (!is_mst)
> +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> +
> +	intel_dp_sink_set_decompression_state(intel_dp, crtc_state, true);
> +	/*
> +	 * DDI FEC: "anticipates enabling FEC encoding sets the FEC_READY bit
> +	 * in the FEC_CONFIGURATION register to 1 before initiating link
> +	 * training
> +	 */
> +	intel_dp_sink_set_fec_ready(intel_dp, crtc_state);
> +	/* 7.c, 7.h, 7.i, 7.j */
> +	intel_dp_start_link_train(intel_dp);
> +
> +	/* 7.k */
> +	intel_dp_stop_link_train(intel_dp);

intel_ddi_enable_fec(encoder, crtc_state); call before dsc_enable call is missing

Manasi

> +
> +	/* 7.l */
> +	intel_dsc_enable(encoder, crtc_state);
> +}
> +
> +static void hsw_ddi_pre_enable_dp(struct intel_encoder *encoder,
> +				  const struct intel_crtc_state *crtc_state,
> +				  const struct drm_connector_state *conn_state)
>  {
>  	struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
>  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> @@ -3228,6 +3346,18 @@ static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
>  	intel_dsc_enable(encoder, crtc_state);
>  }
>  
> +static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
> +				    const struct intel_crtc_state *crtc_state,
> +				    const struct drm_connector_state *conn_state)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> +
> +	if (INTEL_GEN(dev_priv) >= 12)
> +		tgl_ddi_pre_enable_dp(encoder, crtc_state, conn_state);
> +	else
> +		hsw_ddi_pre_enable_dp(encoder, crtc_state, conn_state);
> +}
> +
>  static void intel_ddi_pre_enable_hdmi(struct intel_encoder *encoder,
>  				      const struct intel_crtc_state *crtc_state,
>  				      const struct drm_connector_state *conn_state)
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 5c45a3bb102d..1a59c50f7e0a 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -3950,13 +3950,13 @@ void intel_dp_set_idle_link_train(struct intel_dp *intel_dp)
>  	I915_WRITE(DP_TP_CTL(port), val);
>  
>  	/*
> -	 * On PORT_A we can have only eDP in SST mode. There the only reason
> -	 * we need to set idle transmission mode is to work around a HW issue
> -	 * where we enable the pipe while not in idle link-training mode.
> +	 * Until TGL on PORT_A we can have only eDP in SST mode. There the only
> +	 * reason we need to set idle transmission mode is to work around a HW
> +	 * issue where we enable the pipe while not in idle link-training mode.
>  	 * In this case there is requirement to wait for a minimum number of
>  	 * idle patterns to be sent.
>  	 */
> -	if (port == PORT_A)
> +	if (port == PORT_A && INTEL_GEN(dev_priv) < 12)
>  		return;
>  
>  	if (intel_de_wait_for_set(dev_priv, DP_TP_STATUS(port),
> -- 
> 2.22.1
> 
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