Re: [Intel-gfx] [PATCH 1/5] drm/i915: Skip vswing programming for TBT

[Imre Deak <imre.deak@intel.com>]

On Thu, Jan 28, 2021 at 05:59:44PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> In thunderbolt mode the PHY is owned by the thunderbolt controller.
> We are not supposed to touch it. So skip the vswing programming
> as well (we already skipped the other steps not applicable to TBT).
> 
> Touching this stuff could supposedly interfere with the PHY
> programming done by the thunderbolt controller.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Matches the spec:
Reviewed-by: Imre Deak <imre.deak@intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_ddi.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index 9506b8048530..c94650488dc1 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -2827,6 +2827,9 @@ static void icl_mg_phy_ddi_vswing_sequence(struct intel_encoder *encoder,
>  	int n_entries, ln;
>  	u32 val;
>  
> +	if (enc_to_dig_port(encoder)->tc_mode == TC_PORT_TBT_ALT)
> +		return;
> +
>  	ddi_translations = icl_get_mg_buf_trans(encoder, crtc_state, &n_entries);
>  
>  	if (drm_WARN_ON_ONCE(&dev_priv->drm, !ddi_translations))
> @@ -2962,6 +2965,9 @@ tgl_dkl_phy_ddi_vswing_sequence(struct intel_encoder *encoder,
>  	u32 val, dpcnt_mask, dpcnt_val;
>  	int n_entries, ln;
>  
> +	if (enc_to_dig_port(encoder)->tc_mode == TC_PORT_TBT_ALT)
> +		return;
> +
>  	ddi_translations = tgl_get_dkl_buf_trans(encoder, crtc_state, &n_entries);
>  
>  	if (drm_WARN_ON_ONCE(&dev_priv->drm, !ddi_translations))
> -- 
> 2.26.2
> 
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