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

["Nautiyal, Ankit K" <ankit.k.nautiyal@intel.com>]

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.

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
>>