[Intel-gfx] [PATCH] drm/i915: Fix TGL DKL PHY DP vswing handling

[Souza, Jose]

On Thu, 2020-10-01 at 01:36 +0300, Ville Syrjala wrote:
> From: Ville Syrjälä <
> ville.syrjala at linux.intel.com
> >
> 
> The HDMI vs. not-HDMI check got inverted whem the bogus encoder->type
> checks were eliminated. So now we're using 0 as the link rate on DP
> and potentially non-zero on HDMI, which is exactly the opposite of
> what we want. The original bogus check actually worked more correctly
> by accident since if would always evaluate to true. Due to this we
> now always use the RBR/HBR1 vswing table and never ever the HBR2+
> vswing table. That is probably not a good way to get a high quality
> signal at HBR2+ rates. Fix the check so we pick the right table.
> 

Reviewed-by: José Roberto de Souza <jose.souza at intel.com>

> Cc: 
> stable at vger.kernel.org
> 
> Cc: Vandita Kulkarni <
> vandita.kulkarni at intel.com
> >
> Cc: Uma Shankar <
> uma.shankar at intel.com
> >
> Fixes: 94641eb6c696 ("drm/i915/display: Fix the encoder type check")
> Signed-off-by: Ville Syrjälä <
> ville.syrjala at linux.intel.com
> >
> ---
>  drivers/gpu/drm/i915/display/intel_ddi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index 4d06178cd76c..cdcb7b1034ae 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -2742,7 +2742,7 @@ tgl_dkl_phy_ddi_vswing_sequence(struct intel_encoder *encoder, int link_clock,
>  	u32 n_entries, val, ln, dpcnt_mask, dpcnt_val;
>  	int rate = 0;
>  
> -	if (type == INTEL_OUTPUT_HDMI) {
> +	if (type != INTEL_OUTPUT_HDMI) {
>  		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
>  
>  		rate = intel_dp->link_rate;
>