Re: [PATCH] drm/i915/icl: remove port A/E lane sharing limitation.

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

On Fri, 02 Feb 2018, Mahesh Kumar <mahesh1.kumar@intel.com> wrote:
> Platforms before Gen11 were sharing lanes between port-A & port-E.
> This limitation is no more there.
>
> Changes since V1:
>  - optimize the code (Shashank/Jani)
>  - create helper function to get max lanes (ville)
> Changes since V2:
>  - Include BIOS fail fix-up in same helper function (ville)
>
> Signed-off-by: Mahesh Kumar <mahesh1.kumar@intel.com>
> Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_ddi.c | 71 +++++++++++++++++++---------------------
>  1 file changed, 33 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index cfcd9cb37d5d..ee9ba78d19c8 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -2842,39 +2842,44 @@ static bool intel_ddi_a_force_4_lanes(struct intel_digital_port *dport)
>  	return false;
>  }
>  
> +static int
> +intel_ddi_max_lanes(struct drm_i915_private *dev_priv,
> +		    struct intel_digital_port *intel_dig_port)
> +{

Please ditch the dev_priv parameter and add:

	struct drm_i915_private *dev_priv = to_i915(dport->base.base.dev);

> +	enum port port = intel_dig_port->base.port;
> +	int max_lanes = 4;

Unnecessary initialization.

> +
> +	if (INTEL_GEN(dev_priv) >= 11) {
> +		return 4;

Please either set max_lanes = 4 here, or remove the else. On early
returns, you don't need the else. Having both is confusing.

> +	} else if (port == PORT_A || port == PORT_E) {
> +		if (I915_READ(DDI_BUF_CTL(PORT_A)) & DDI_A_4_LANES)
> +			max_lanes = port == PORT_A ? 4 : 0;
> +		else
> +			/* Both A and E share 2 lanes */
> +			max_lanes = 2;
> +	}
> +
> +	/*
> +	 * Some BIOS might fail to set this bit on port A if eDP
> +	 * wasn't lit up at boot.  Force this bit set when needed
> +	 * so we use the proper lane count for our calculations.
> +	 */
> +	if (intel_ddi_a_force_4_lanes(intel_dig_port)) {
> +		DRM_DEBUG_KMS("Forcing DDI_A_4_LANES for port A\n");
> +		intel_dig_port->saved_port_bits |= DDI_A_4_LANES;
> +		max_lanes = 4;
> +	}
> +
> +	return max_lanes;
> +}
> +
>  void intel_ddi_init(struct drm_i915_private *dev_priv, enum port port)
>  {
>  	struct intel_digital_port *intel_dig_port;
>  	struct intel_encoder *intel_encoder;
>  	struct drm_encoder *encoder;
>  	bool init_hdmi, init_dp, init_lspcon = false;
> -	int max_lanes;
>  
> -	if (I915_READ(DDI_BUF_CTL(PORT_A)) & DDI_A_4_LANES) {
> -		switch (port) {
> -		case PORT_A:
> -			max_lanes = 4;
> -			break;
> -		case PORT_E:
> -			max_lanes = 0;
> -			break;
> -		default:
> -			max_lanes = 4;
> -			break;
> -		}
> -	} else {
> -		switch (port) {
> -		case PORT_A:
> -			max_lanes = 2;
> -			break;
> -		case PORT_E:
> -			max_lanes = 2;
> -			break;
> -		default:
> -			max_lanes = 4;
> -			break;
> -		}
> -	}
>  
>  	init_hdmi = (dev_priv->vbt.ddi_port_info[port].supports_dvi ||
>  		     dev_priv->vbt.ddi_port_info[port].supports_hdmi);
> @@ -2954,19 +2959,7 @@ void intel_ddi_init(struct drm_i915_private *dev_priv, enum port port)
>  		MISSING_CASE(port);
>  	}
>  
> -	/*
> -	 * Some BIOS might fail to set this bit on port A if eDP
> -	 * wasn't lit up at boot.  Force this bit set when needed
> -	 * so we use the proper lane count for our calculations.
> -	 */
> -	if (intel_ddi_a_force_4_lanes(intel_dig_port)) {
> -		DRM_DEBUG_KMS("Forcing DDI_A_4_LANES for port A\n");
> -		intel_dig_port->saved_port_bits |= DDI_A_4_LANES;
> -		max_lanes = 4;
> -	}
> -
>  	intel_dig_port->dp.output_reg = INVALID_MMIO_REG;
> -	intel_dig_port->max_lanes = max_lanes;
>  
>  	intel_encoder->type = INTEL_OUTPUT_DDI;
>  	intel_encoder->power_domain = intel_port_to_power_domain(port);
> @@ -2974,6 +2967,8 @@ void intel_ddi_init(struct drm_i915_private *dev_priv, enum port port)
>  	intel_encoder->crtc_mask = (1 << 0) | (1 << 1) | (1 << 2);
>  	intel_encoder->cloneable = 0;
>  
> +	intel_dig_port->max_lanes = intel_ddi_max_lanes(dev_priv,
> +							intel_dig_port);

Please keep this at the original location above.

BR,
Jani.

>  	intel_infoframe_init(intel_dig_port);
>  
>  	if (init_dp) {

-- 
Jani Nikula, Intel Open Source Technology Center
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