Re: [PATCH 1/5] drm/i915: Use intel_ddi_dp_voltage_max() for HSW/BDW too

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

On Thu, 17 May 2018, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Use intel_ddi_dp_voltage_max() for HSW/BDW too instead of letting these
> fall through the if ladder in a weird way. This function will look at
> the actual buf trans tables we have for HSW/BDW to determine the max
> vswing level.
>
> It looks to me like the current code leads HSW port A down the IVB port
> A path, HSW port B+ and BDW fall through to the very end. Both cases do
> result in the correct max vswing level 2, but it's very hard to see that
> from the code.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

What a PITA patch to review that there are no functional changes!

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  drivers/gpu/drm/i915/intel_dp.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 2cc58596ff5a..4755bb1b0b40 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -3220,12 +3220,12 @@ uint8_t
>  intel_dp_voltage_max(struct intel_dp *intel_dp)
>  {
>  	struct drm_i915_private *dev_priv = to_i915(intel_dp_to_dev(intel_dp));
> -	enum port port = dp_to_dig_port(intel_dp)->base.port;
> +	struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)->base;
> +	enum port port = encoder->port;
>  
> -	if (INTEL_GEN(dev_priv) >= 9) {
> -		struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)->base;
> +	if (HAS_DDI(dev_priv))
>  		return intel_ddi_dp_voltage_max(encoder);
> -	} else if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
> +	else if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
>  		return DP_TRAIN_VOLTAGE_SWING_LEVEL_3;
>  	else if (IS_GEN7(dev_priv) && port == PORT_A)
>  		return DP_TRAIN_VOLTAGE_SWING_LEVEL_2;

-- 
Jani Nikula, Intel Open Source Graphics Center
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