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

[Pandiyan, Dhinakaran]

On Tue, 2018-01-30 at 14:51 +0530, Mahesh Kumar wrote:
> From: "Kumar, Mahesh" <mahesh1.kumar at intel.com>
> 
> 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)
> 
> Signed-off-by: Mahesh Kumar <mahesh1.kumar at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_ddi.c | 43 +++++++++++++++++-----------------------
>  1 file changed, 18 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index e51559be2e3b..4bde742a8ff4 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -2842,6 +2842,23 @@ 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, enum port port)
> +{
> +	if (INTEL_GEN(dev_priv) >= 11)
> +		return 4;
> +
> +	if (port == PORT_A || port == PORT_E) {
> +		if (I915_READ(DDI_BUF_CTL(PORT_A)) & DDI_A_4_LANES)


Is the expectation that bios has already written the correct value
depending on the board?

The patch itself looks correct 
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>



> +			return port == PORT_A ? 4 : 0;
> +		else
> +			/* Both A and E share 2 lanes */
> +			return 2;
> +	}
> +
> +	return 4;
> +}
> +
>  void intel_ddi_init(struct drm_i915_private *dev_priv, enum port port)
>  {
>  	struct intel_digital_port *intel_dig_port;
> @@ -2850,31 +2867,7 @@ void intel_ddi_init(struct drm_i915_private *dev_priv, enum port port)
>  	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;
> -		}
> -	}
> +	max_lanes = intel_ddi_max_lanes(dev_priv, port);
>  
>  	init_hdmi = (dev_priv->vbt.ddi_port_info[port].supports_dvi ||
>  		     dev_priv->vbt.ddi_port_info[port].supports_hdmi);