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 06:07:44PM +0530, Nautiyal, Ankit K wrote:
> 
> On 2/5/2026 3:11 PM, Imre Deak wrote:
> > 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.
> 
> Since this function is called from the iterator macro for DP MST also, I was
> wondering if for MST case we need to get it via encoder/dig_port.

No, intel_attached_dp() works for MST connectors as well.

> Regards,
> 
> Ankit
> 
> 
> > 
> > >   {
> > >   	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
> > >