Re: [PATCH] drm/i915/display: Limit the eDP joiner to the pipe A and B pair

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Nov 06, 2026 at 09:41:13AM +0000, Mika Kahola wrote:
> eDP only works joined as the pipe A and B pair, other consecutive pairs
> fail to come up.

There is no such restriction. Just tried it on a PTL here and it works
just fine.

> Keep the eDP joiner primary on pipe A. DP and unjoined
> eDP are unaffected.
> 
> Signed-off-by: Mika Kahola <mika.kahola@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 21 ++++++++++++++++-----
>  1 file changed, 16 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index ef164a797618..b359a66a018f 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1362,16 +1362,27 @@ static int intel_dp_mso_pixel_clock(struct intel_dp *intel_dp, int pixel_clock)
>  	return pixel_clock / intel_dp->mso_link_count;
>  }
>  
> +/* eDP can only be joined as the pipe A and B pair. */
> +static u8 intel_dp_joiner_valid_primary_pipe_mask(struct intel_dp *intel_dp,
> +						  int num_joined_pipes)
> +{
> +	struct intel_display *display = to_intel_display(intel_dp);
> +	u8 pipe_mask = intel_joiner_valid_primary_pipe_mask(display, num_joined_pipes);
> +
> +	if (num_joined_pipes > 1 && intel_dp_is_edp(intel_dp))
> +		pipe_mask &= BIT(PIPE_A);
> +
> +	return pipe_mask;
> +}
> +
>  static
>  bool intel_dp_can_join(struct intel_dp *intel_dp,
>  		       int num_joined_pipes)
>  {
> -	struct intel_display *display = to_intel_display(intel_dp);
> -
>  	if (num_joined_pipes > 1 && !intel_dp_has_joiner(intel_dp))
>  		return false;
>  
> -	return intel_joiner_valid_primary_pipe_mask(display, num_joined_pipes);
> +	return intel_dp_joiner_valid_primary_pipe_mask(intel_dp, num_joined_pipes);
>  }
>  
>  bool intel_dp_dotclk_valid(struct intel_display *display,
> @@ -3083,7 +3094,6 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
>  			     struct drm_connector_state *conn_state,
>  			     bool respect_downstream_limits)
>  {
> -	struct intel_display *display = to_intel_display(encoder);
>  	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
>  	struct intel_connector *connector =
>  		to_intel_connector(conn_state->connector);
> @@ -3099,7 +3109,8 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
>  
>  	for_each_joiner_candidate(connector, adjusted_mode, num_joined_pipes) {
>  		/* If the pipe can't be a joiner primary, skip early. */
> -		if (!(intel_joiner_valid_primary_pipe_mask(display, num_joined_pipes) & BIT(crtc->pipe)))
> +		if (!(intel_dp_joiner_valid_primary_pipe_mask(intel_dp, num_joined_pipes) &
> +		      BIT(crtc->pipe)))
>  			continue;
>  
>  		/*
> -- 
> 2.43.0

-- 
Ville Syrjälä
Intel