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

[Jani Nikula]

On Wed, 16 Mar 2016, Mika Kahola <mika.kahola at intel.com> wrote:
> [ text/plain ]
> 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.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94087
> Signed-off-by: Mika Kahola <mika.kahola at intel.com>

cc: stable?

> ---
>  drivers/gpu/drm/i915/intel_ddi.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index ab025a5..e30adcd 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -443,9 +443,19 @@ 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->edp_low_vswing)
> +			ddi_translations_edp = bdw_ddi_translations_edp;
> +		else
> +			ddi_translations_edp = bdw_ddi_translations_dp;
> +
>  		ddi_translations_hdmi = bdw_ddi_translations_hdmi;
> -		n_edp_entries = ARRAY_SIZE(bdw_ddi_translations_edp);
> +
> +		if (dev_priv->edp_low_vswing)
> +			n_edp_entries = ARRAY_SIZE(bdw_ddi_translations_edp);
> +		else
> +			n_edp_entries = ARRAY_SIZE(bdw_ddi_translations_dp);
> +

Please just put these in one if statement above, instead of having two.

BR,
Jani.

>  		n_dp_entries = ARRAY_SIZE(bdw_ddi_translations_dp);
>  		n_hdmi_entries = ARRAY_SIZE(bdw_ddi_translations_hdmi);
>  		hdmi_default_entry = 7;

-- 
Jani Nikula, Intel Open Source Technology Center