Re: [PATCH 8/8] drm/i915/cnl: Fix DP max voltage

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Aug 29, 2017 at 04:22:30PM -0700, Rodrigo Vivi wrote:
> On clock recovery this function is called to find out
> the max voltage swing level that we could go.
> 
> However gen 9 functions use the old buffer translation tables
> to figure that out. That table is not valid for CNL
> causing an invalid number of entries and an invalid selection
> on the max voltage swing level.
> 
> v2: Let's use same approach that previous platforms.
> 
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Clint Taylor <clinton.a.taylor@intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_ddi.c | 35 +++++++++++++++++++++++++++++++----
>  1 file changed, 31 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index f1757a8e481a..97ff082c28a7 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -649,6 +649,29 @@ cnl_get_buf_trans_edp(struct drm_i915_private *dev_priv, int *n_entries)
>  	}
>  }
>  
> +static int cnl_max_level(struct drm_i915_private *dev_priv,
> +			 enum intel_output_type type)
> +{
> +	int n_entries = 0;
> +
> +	switch (type) {
> +	case INTEL_OUTPUT_DP:

These encoder->type checks are a bit problematic due to the DDI encoder
type changing dynamically. But to fix that I thunk I'll just need to
resurrect my old patches to get rid of that type changing. But I'll
wait until you cand land these since I need to rebase my stuff anyway.

> +		cnl_get_buf_trans_dp(dev_priv, &n_entries);
> +		break;
> +	case INTEL_OUTPUT_EDP:
> +		cnl_get_buf_trans_edp(dev_priv, &n_entries);
> +		break;
> +	case INTEL_OUTPUT_HDMI:
> +		cnl_get_buf_trans_hdmi(dev_priv, &n_entries);
> +		break;
> +	default:
> +		MISSING_CASE(type);
> +		return 0;
> +	}
> +
> +	return n_entries - 1;
> +}
> +
>  static int intel_ddi_hdmi_level(struct drm_i915_private *dev_priv, enum port port)
>  {
>  	int n_hdmi_entries;
> @@ -1879,10 +1902,14 @@ u8 intel_ddi_dp_voltage_max(struct intel_encoder *encoder)
>  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
>  	int n_entries;
>  
> -	if (encoder->type == INTEL_OUTPUT_EDP)
> -		intel_ddi_get_buf_trans_edp(dev_priv, &n_entries);
> -	else
> -		intel_ddi_get_buf_trans_dp(dev_priv, &n_entries);
> +	if (IS_CANNONLAKE(dev_priv)) {
> +		cnl_max_level(dev_priv, encoder->type);
> +	} else {
> +		if (encoder->type == INTEL_OUTPUT_EDP)
> +			intel_ddi_get_buf_trans_edp(dev_priv, &n_entries);
> +		else
> +			intel_ddi_get_buf_trans_dp(dev_priv, &n_entries);
> +	}
>  
>  	if (WARN_ON(n_entries < 1))
>  		n_entries = 1;
> -- 
> 2.13.2

-- 
Ville Syrjälä
Intel OTC
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