[Intel-gfx] [PATCH 2/6] drm/dp: Kill unused MST vcpi slot availability tracking

[Dhinakaran Pandiyan]

The avail_slots member in the MST topology manager is never updated to
reflect the available vcpi slots. The check is effectively against
total_slots. So, let's make that check obvious. Secondly, since the total
vcpi time slots is always 63 and does not depend on the link BW, remove
total_slots from MST topology manager struct. The third change is to
remove total_pbn which is hardcoded to 2560. The total PBN that the
topology manager allocates from depends on the link rate and is not a
constant. So, fix this by removing the total_pbn member itself.

Finally, make debug messages more informative.

Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 14 ++++++--------
 include/drm/drm_dp_mst_helper.h       | 12 ------------
 2 files changed, 6 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 122a1b0..5df00ae 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2042,10 +2042,6 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms
 			goto out_unlock;
 		}
 
-		mgr->total_pbn = 2560;
-		mgr->total_slots = DIV_ROUND_UP(mgr->total_pbn, mgr->pbn_div);
-		mgr->avail_slots = mgr->total_slots;
-
 		/* add initial branch device at LCT 1 */
 		mstb = drm_dp_add_mst_branch_device(1, NULL);
 		if (mstb == NULL) {
@@ -2475,7 +2471,8 @@ int drm_dp_find_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr,
 
 	num_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
 
-	if (num_slots > mgr->avail_slots)
+	/* max. time slots - one slot for MTP header */
+	if (num_slots > 63)
 		return -ENOSPC;
 	return num_slots;
 }
@@ -2489,7 +2486,8 @@ static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,
 
 	num_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
 
-	if (num_slots > mgr->avail_slots)
+	/* max. time slots - one slot for MTP header */
+	if (num_slots > 63)
 		return -ENOSPC;
 
 	vcpi->pbn = pbn;
@@ -2528,10 +2526,10 @@ bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp
 
 	ret = drm_dp_init_vcpi(mgr, &port->vcpi, pbn);
 	if (ret) {
-		DRM_DEBUG_KMS("failed to init vcpi %d %d %d\n", DIV_ROUND_UP(pbn, mgr->pbn_div), mgr->avail_slots, ret);
+		DRM_DEBUG_KMS("failed to init vcpi slots=%d max=63 ret=%d\n", DIV_ROUND_UP(pbn, mgr->pbn_div), ret);
 		goto out;
 	}
-	DRM_DEBUG_KMS("initing vcpi for %d %d\n", pbn, port->vcpi.num_slots);
+	DRM_DEBUG_KMS("initing vcpi for pbn=%d slots=%d\n", pbn, port->vcpi.num_slots);
 	*slots = port->vcpi.num_slots;
 
 	drm_dp_put_port(port);
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index 27f3e99..b0f4a09 100644
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -479,18 +479,6 @@ struct drm_dp_mst_topology_mgr {
 	 * @pbn_div: PBN to slots divisor.
 	 */
 	int pbn_div;
-	/**
-	 * @total_slots: Total slots that can be allocated.
-	 */
-	int total_slots;
-	/**
-	 * @avail_slots: Still available slots that can be allocated.
-	 */
-	int avail_slots;
-	/**
-	 * @total_pbn: Total PBN count.
-	 */
-	int total_pbn;
 
 	/**
 	 * @qlock: protects @tx_msg_downq, the tx_slots in struct
-- 
2.7.4