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

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

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.

v2: Derive intel_dp from intel_attached_dp(). (Imre)

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 | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 4f5b89f80e55..7da4310b399e 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;
@@ -7218,8 +7223,9 @@ bool intel_dp_joiner_candidate_valid(struct intel_connector *connector,
 				     int num_joined_pipes)
 {
 	struct intel_display *display = to_intel_display(connector);
+	struct intel_dp *intel_dp = intel_attached_dp(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))
-- 
2.45.2