[Intel-gfx] [PATCH] drm/i915/dp/mst: Validate modes against the available link bandwidth

[Anusha Srivatsa]

Change intel_dp_mst_mode_valid() to use available link bandwidth
rather than the link's maximum supported bandwidth to evaluate
whether modes are legal for the current configuration. This takes
into account the fact that link bandwidth may already be dedicated
to other virtual channels.

Signed-off-by: Anusha Srivatsa <anusha.srivatsa at intel.com>
---
 drivers/gpu/drm/i915/intel_dp_mst.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
index 629337d..39c58eb 100644
--- a/drivers/gpu/drm/i915/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -352,16 +352,22 @@ static enum drm_mode_status
 intel_dp_mst_mode_valid(struct drm_connector *connector,
 			struct drm_display_mode *mode)
 {
-	int max_dotclk = to_i915(connector->dev)->max_dotclk_freq;
+	int req_pbn = 0;
+	int slots = 0;
+	struct intel_connector *intel_connector = to_intel_connector(connector);
+	struct intel_dp *intel_dp = intel_connector->mst_port;
+	struct drm_dp_mst_topology_mgr *mgr = &intel_dp->mst_mgr;
+
+	req_pbn = drm_dp_calc_pbn_mode(mode->clock, 24);
+	slots = drm_dp_find_vcpi_slots(mgr, req_pbn);
 
-	/* TODO - validate mode against available PBN for link */
 	if (mode->clock < 10000)
 		return MODE_CLOCK_LOW;
 
 	if (mode->flags & DRM_MODE_FLAG_DBLCLK)
 		return MODE_H_ILLEGAL;
 
-	if (mode->clock > max_dotclk)
+	if (slots == -ENOSPC)
 		return MODE_CLOCK_HIGH;
 
 	return MODE_OK;
-- 
2.7.4