[Intel-gfx] [PATCH v3] drm/i915: Fix eDP low vswing for Broadwell

[Ville Syrjälä]

On Wed, Apr 20, 2016 at 03:39:02PM +0300, Mika Kahola wrote:
> It was noticed on bug #94087 that module parameter
> i915.edp_vswing=2 that should override the VBT setting
> to use default voltage swing (400 mV) was not applied
> for Broadwell.
> 
> This patch provides a fix for this by checking if default
> i.e. higher voltage swing is requested to be used and
> applies the DDI translations table for DP instead of eDP
> (low vswing) table.
> 
> v2: Combine two if statements into one (Jani)
> v3: Change dev_priv->edp_low_vswing to use dev_priv->vbt.edp.low_vswing
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94087
> Signed-off-by: Mika Kahola <mika.kahola at intel.com>

Patch pushed to dinq, with cc:stable.

> ---
>  drivers/gpu/drm/i915/intel_ddi.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index c2348fb..a887b31 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -443,9 +443,17 @@ void intel_prepare_ddi_buffer(struct intel_encoder *encoder)
>  	} else if (IS_BROADWELL(dev_priv)) {
>  		ddi_translations_fdi = bdw_ddi_translations_fdi;
>  		ddi_translations_dp = bdw_ddi_translations_dp;
> -		ddi_translations_edp = bdw_ddi_translations_edp;
> +
> +		if (dev_priv->vbt.edp.low_vswing) {
> +			ddi_translations_edp = bdw_ddi_translations_edp;
> +			n_edp_entries = ARRAY_SIZE(bdw_ddi_translations_edp);
> +		} else {
> +			ddi_translations_edp = bdw_ddi_translations_dp;
> +			n_edp_entries = ARRAY_SIZE(bdw_ddi_translations_dp);
> +		}
> +
>  		ddi_translations_hdmi = bdw_ddi_translations_hdmi;
> -		n_edp_entries = ARRAY_SIZE(bdw_ddi_translations_edp);
> +
>  		n_dp_entries = ARRAY_SIZE(bdw_ddi_translations_dp);
>  		n_hdmi_entries = ARRAY_SIZE(bdw_ddi_translations_hdmi);
>  		hdmi_default_entry = 7;
> -- 
> 1.9.1
> 
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-- 
Ville Syrjälä
Intel OTC