Re: [PATCH v10 22/23] i915/dp/fec: Configure the Forward Error Correction bits.

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

On Tue, Nov 20, 2018 at 10:37:35AM -0800, Manasi Navare wrote:
> From: Anusha Srivatsa <anusha.srivatsa@intel.com>
> 
> If FEC is supported, the corresponding
> DP_TP_CTL register bits have to be configured.
> 
> The driver has to program the FEC_ENABLE in DP_TP_CTL[30] register
> and wait till FEC_STATUS in DP_TP_CTL[28] is 1.
> Also add the warn message to make sure that the control
> register is already active while enabling FEC.
> 
> v2:
> - Change commit message. Configure fec state after
>   link training (Manasi, Gaurav)
> - Remove redundent checks (Manasi)
> - Remove the registers that get added automagically (Anusha)
> 
> v3: s/intel_dp_set_fec_state()/intel_dp_enable_fec_state() (Gaurav)
> 
> v4: rebased.
> 
> v5:
> - Move the code to the proper spot, according to spec.(Ville)
> - Use fec state as a check too.
> 
> v6: Pass intel_encoder, instead of intel_dp. (Ville)
> 
> v7: Remove unwanted comments (Manasi)
> 
> Cc: dri-devel@lists.freedesktop.org
> Cc: Gaurav K Singh <gaurav.k.singh@intel.com>
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
> Cc: Manasi Navare <manasi.d.navare@intel.com>
> Signed-off-by: Anusha Srivatsa <anusha.srivatsa@intel.com>

Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>

Manasi

> ---
>  drivers/gpu/drm/i915/i915_reg.h  |  2 ++
>  drivers/gpu/drm/i915/intel_ddi.c | 23 +++++++++++++++++++++++
>  2 files changed, 25 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 21e82c03cf80..5713754ace99 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -9198,6 +9198,7 @@ enum skl_power_gate {
>  #define _DP_TP_CTL_B			0x64140
>  #define DP_TP_CTL(port) _MMIO_PORT(port, _DP_TP_CTL_A, _DP_TP_CTL_B)
>  #define  DP_TP_CTL_ENABLE			(1 << 31)
> +#define  DP_TP_CTL_FEC_ENABLE			(1 << 30)
>  #define  DP_TP_CTL_MODE_SST			(0 << 27)
>  #define  DP_TP_CTL_MODE_MST			(1 << 27)
>  #define  DP_TP_CTL_FORCE_ACT			(1 << 25)
> @@ -9216,6 +9217,7 @@ enum skl_power_gate {
>  #define _DP_TP_STATUS_A			0x64044
>  #define _DP_TP_STATUS_B			0x64144
>  #define DP_TP_STATUS(port) _MMIO_PORT(port, _DP_TP_STATUS_A, _DP_TP_STATUS_B)
> +#define  DP_TP_STATUS_FEC_ENABLE_LIVE		(1 << 28)
>  #define  DP_TP_STATUS_IDLE_DONE			(1 << 25)
>  #define  DP_TP_STATUS_ACT_SENT			(1 << 24)
>  #define  DP_TP_STATUS_MODE_STATUS_MST		(1 << 23)
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index b778e6fed5f8..78d8dcaa1618 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -3112,6 +3112,27 @@ static void intel_dp_sink_set_fec_ready(struct intel_dp *intel_dp,
>  		DRM_DEBUG_KMS("Failed to set FEC_READY in the sink\n");
>  }
>  
> +static void intel_ddi_enable_fec(struct intel_encoder *encoder,
> +				 const struct intel_crtc_state *crtc_state)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> +	enum port port = encoder->port;
> +	u32 val;
> +
> +	if (!crtc_state->fec_enable)
> +		return;
> +
> +	val = I915_READ(DP_TP_CTL(port));
> +	val |= DP_TP_CTL_FEC_ENABLE;
> +	I915_WRITE(DP_TP_CTL(port), val);
> +
> +	if (intel_wait_for_register(dev_priv, DP_TP_STATUS(port),
> +				    DP_TP_STATUS_FEC_ENABLE_LIVE,
> +				    DP_TP_STATUS_FEC_ENABLE_LIVE,
> +				    1))
> +		DRM_ERROR("Timed out waiting for FEC Enable Status\n");
> +}
> +
>  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)
> @@ -3157,6 +3178,8 @@ static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
>  	if (port != PORT_A || INTEL_GEN(dev_priv) >= 9)
>  		intel_dp_stop_link_train(intel_dp);
>  
> +	intel_ddi_enable_fec(encoder, crtc_state);
> +
>  	icl_enable_phy_clock_gating(dig_port);
>  
>  	if (!is_mst)
> -- 
> 2.19.1
> 
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