Re: [PATCH 2/2] drm/i915/dp: Restore the missing check for intel_dp_has_joiner

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

On Thu, Feb 05, 2026 at 02:06:23PM +0530, Ankit Nautiyal wrote:
> Commit ad121a62d566 ("drm/i915/dp: Rework pipe joiner logic in mode_valid")
> replaced intel_dp_num_joined_pipes() with an explicit joiner candidate
> iteration. The previous code implicitly checked for DP joiner capability
> via intel_dp_has_joiner(), but this check was lost during the refactor.
> 
> Restore the missing intel_dp_has_joiner() check in intel_dp_can_join() so
> that DP specific joiner conditions are taken into account.
> 
> This change also requires propagating struct intel_dp * from the callers
> down to the new check.
> 
> Fixes: ad121a62d566 ("drm/i915/dp: Rework pipe joiner logic in mode_valid")
> Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> Cc: Imre Deak <imre.deak@intel.com>
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp.c     | 16 +++++++++++-----
>  drivers/gpu/drm/i915/display/intel_dp.h     |  7 ++++---
>  drivers/gpu/drm/i915/display/intel_dp_mst.c |  4 ++--
>  3 files changed, 17 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 4f5b89f80e55..3021c64d0f85 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1397,9 +1397,14 @@ bool intel_dp_has_dsc(const struct intel_connector *connector)
>  }
>  
>  static
> -bool intel_dp_can_join(struct intel_display *display,
> +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;
> +
>  	switch (num_joined_pipes) {
>  	case 1:
>  		return true;
> @@ -1496,7 +1501,7 @@ intel_dp_mode_valid(struct drm_connector *_connector,
>  	 * over candidate pipe counts and evaluate each combination.
>  	 */
>  	status = MODE_CLOCK_HIGH;
> -	for_each_joiner_candidate(connector, mode, num_joined_pipes) {
> +	for_each_joiner_candidate(intel_dp, connector, mode, num_joined_pipes) {
>  		int dsc_slice_count = 0;
>  
>  		status = intel_pfit_mode_valid(display, mode, output_format, num_joined_pipes);
> @@ -2895,7 +2900,7 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
>  	    !intel_dp_supports_fec(intel_dp, connector, crtc_state))
>  		return -EINVAL;
>  
> -	for_each_joiner_candidate(connector, adjusted_mode, num_joined_pipes) {
> +	for_each_joiner_candidate(intel_dp, connector, adjusted_mode, num_joined_pipes) {
>  		/*
>  		 * NOTE:
>  		 * The crtc_state->joiner_pipes should have been set at the end
> @@ -7213,13 +7218,14 @@ int intel_dp_sdp_min_guardband(const struct intel_crtc_state *crtc_state,
>  	return sdp_guardband;
>  }
>  
> -bool intel_dp_joiner_candidate_valid(struct intel_connector *connector,
> +bool intel_dp_joiner_candidate_valid(struct intel_dp *intel_dp,
> +				     struct intel_connector *connector,
>  				     int hdisplay,
>  				     int num_joined_pipes)

intel_dp can be always deducted from the connector, via
intel_attached_dp(), so no need to pass intel_dp separately.

>  {
>  	struct intel_display *display = to_intel_display(connector);
>  
> -	if (!intel_dp_can_join(display, num_joined_pipes))
> +	if (!intel_dp_can_join(intel_dp, num_joined_pipes))
>  		return false;
>  
>  	if (hdisplay > num_joined_pipes * intel_dp_max_hdisplay_per_pipe(display))
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h
> index cbd7fcd3789f..37302ebe1cf9 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.h
> +++ b/drivers/gpu/drm/i915/display/intel_dp.h
> @@ -227,12 +227,13 @@ bool intel_dp_dotclk_valid(struct intel_display *display,
>  			   int htotal,
>  			   int dsc_slice_count,
>  			   int num_joined_pipes);
> -bool intel_dp_joiner_candidate_valid(struct intel_connector *connector,
> +bool intel_dp_joiner_candidate_valid(struct intel_dp *intel_dp,
> +				     struct intel_connector *connector,
>  				     int hdisplay,
>  				     int num_joined_pipes);
>  
> -#define for_each_joiner_candidate(__connector, __mode, __num_joined_pipes) \
> +#define for_each_joiner_candidate(__intel_dp, __connector, __mode, __num_joined_pipes) \
>  	for ((__num_joined_pipes) = 1; (__num_joined_pipes) <= (I915_MAX_PIPES); (__num_joined_pipes)++) \
> -		for_each_if(intel_dp_joiner_candidate_valid(__connector, (__mode)->hdisplay, __num_joined_pipes))
> +		for_each_if(intel_dp_joiner_candidate_valid(__intel_dp, __connector, (__mode)->hdisplay, __num_joined_pipes))
>  
>  #endif /* __INTEL_DP_H__ */
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index 29713075e413..b2d3f35edd78 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -720,7 +720,7 @@ static int mst_stream_compute_config(struct intel_encoder *encoder,
>  	pipe_config->output_format = INTEL_OUTPUT_FORMAT_RGB;
>  	pipe_config->has_pch_encoder = false;
>  
> -	for_each_joiner_candidate(connector, adjusted_mode, num_joined_pipes) {
> +	for_each_joiner_candidate(intel_dp, connector, adjusted_mode, num_joined_pipes) {
>  		if (num_joined_pipes > 1)
>  			pipe_config->joiner_pipes = GENMASK(crtc->pipe + num_joined_pipes - 1,
>  							    crtc->pipe);
> @@ -1524,7 +1524,7 @@ mst_connector_mode_valid_ctx(struct drm_connector *_connector,
>  	}
>  
>  	*status = MODE_CLOCK_HIGH;
> -	for_each_joiner_candidate(connector, mode, num_joined_pipes) {
> +	for_each_joiner_candidate(intel_dp, connector, mode, num_joined_pipes) {
>  		int dsc_slice_count = 0;
>  
>  		if (intel_dp_has_dsc(connector) &&
> -- 
> 2.45.2
>