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

[Kulkarni, Vandita]

> -----Original Message-----
> From: Ville Syrjala <ville.syrjala at linux.intel.com>
> Sent: Thursday, October 1, 2020 4:07 AM
> To: intel-gfx at lists.freedesktop.org
> Cc: stable at vger.kernel.org; Kulkarni, Vandita <vandita.kulkarni at intel.com>;
> Shankar, Uma <uma.shankar at intel.com>
> Subject: [PATCH] drm/i915: Fix TGL DKL PHY DP vswing handling
> 
> 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.
> 
> 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>

LGTM.
Reviewed-by: Vandita Kulkarni <vandita.kulkarni at intel.com>
I think I missed the inverted change while rebasing.
Thanks,
Vandita
> ---
>  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;
> --
> 2.26.2