drm/dp: Split drm_dp_mst_allocate_vcpi

drm_dp_mst_allocate_vcpi() apart from setting up the vcpi structure,
also finds if there are enough slots available. This check is a duplicate
of that implemented in drm_dp_mst_find_vcpi_slots(). Let's move this check
out and reuse the existing drm_dp_mst_find_vcpi_slots() function to check
if there are enough vcpi slots before allocating them.

This brings the check to one place. Additionally drivers that will use MST
state tracking for atomic modesets can use the atomic version of
find_vcpi_slots() and reuse drm_dp_mst_allocate_vcpi()

Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1489648231-30700-4-git-send-email-dhinakaran.pandiyan@intel.com

drivers/gpu/drm/drm_dp_mst_topology.c

@@ -2479,20 +2479,17 @@ int drm_dp_find_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr,
 EXPORT_SYMBOL(drm_dp_find_vcpi_slots);
 
 static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,
-			    struct drm_dp_vcpi *vcpi, int pbn)
+			    struct drm_dp_vcpi *vcpi, int pbn, int slots)
 {
-	int num_slots;
 	int ret;
 
-	num_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
-
 	/* max. time slots - one slot for MTP header */
-	if (num_slots > 63)
+	if (slots > 63)
 		return -ENOSPC;
 
 	vcpi->pbn = pbn;
-	vcpi->aligned_pbn = num_slots * mgr->pbn_div;
-	vcpi->num_slots = num_slots;
+	vcpi->aligned_pbn = slots * mgr->pbn_div;
+	vcpi->num_slots = slots;
 
 	ret = drm_dp_mst_assign_payload_id(mgr, vcpi);
 	if (ret < 0)
@@ -2507,7 +2504,8 @@ static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,
  * @pbn: payload bandwidth number to request
  * @slots: returned number of slots for this PBN.
  */
-bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port, int pbn, int *slots)
+bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
+			      struct drm_dp_mst_port *port, int pbn, int slots)
 {
 	int ret;
 
@@ -2515,16 +2513,18 @@ bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp
 	if (!port)
 		return false;
 
+	if (slots < 0)
+		return false;
+
 	if (port->vcpi.vcpi > 0) {
 		DRM_DEBUG_KMS("payload: vcpi %d already allocated for pbn %d - requested pbn %d\n", port->vcpi.vcpi, port->vcpi.pbn, pbn);
 		if (pbn == port->vcpi.pbn) {
-			*slots = port->vcpi.num_slots;
 			drm_dp_put_port(port);
 			return true;
 		}
 	}
 
-	ret = drm_dp_init_vcpi(mgr, &port->vcpi, pbn);
+	ret = drm_dp_init_vcpi(mgr, &port->vcpi, pbn, slots);
 	if (ret) {
 		DRM_DEBUG_KMS("failed to init vcpi slots=%d max=63 ret=%d\n",
 				DIV_ROUND_UP(pbn, mgr->pbn_div), ret);
@@ -2532,7 +2532,6 @@ bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp
 	}
 	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);
 	return true;

drivers/gpu/drm/i915/intel_dp_mst.c

@@ -147,7 +147,6 @@ static void intel_mst_pre_enable_dp(struct intel_encoder *encoder,
 		to_intel_connector(conn_state->connector);
 	int ret;
 	uint32_t temp;
-	int slots;
 
 	/* MST encoders are bound to a crtc, not to a connector,
 	 * force the mapping here for get_hw_state.
@@ -177,7 +176,8 @@ static void intel_mst_pre_enable_dp(struct intel_encoder *encoder,
 
 	ret = drm_dp_mst_allocate_vcpi(&intel_dp->mst_mgr,
 				       connector->port,
-				       pipe_config->pbn, &slots);
+				       pipe_config->pbn,
+				       pipe_config->dp_m_n.tu);
 	if (ret == false) {
 		DRM_ERROR("failed to allocate vcpi\n");
 		return;

drivers/gpu/drm/nouveau/nv50_display.c

@@ -2895,7 +2895,8 @@ nv50_msto_enable(struct drm_encoder *encoder)
 	if (WARN_ON(!mstc))
 		return;
 
-	r = drm_dp_mst_allocate_vcpi(&mstm->mgr, mstc->port, mstc->pbn, &slots);
+	slots = drm_dp_find_vcpi_slots(&mstm->mgr, mstc->pbn);
+	r = drm_dp_mst_allocate_vcpi(&mstm->mgr, mstc->port, mstc->pbn, slots);
 	WARN_ON(!r);
 
 	if (mstm->outp->dcb->sorconf.link & 1)

drivers/gpu/drm/radeon/radeon_dp_mst.c

@@ -453,9 +453,11 @@ radeon_mst_encoder_dpms(struct drm_encoder *encoder, int mode)
 		DRM_DEBUG_KMS("dig encoder is %d %d %d\n", dig_enc->dig_encoder,
 			      dig_enc->linkb, radeon_crtc->crtc_id);
 
+		slots = drm_dp_find_vcpi_slots(&radeon_connector->mst_port->mst_mgr,
+					       mst_enc->pbn);
 		ret = drm_dp_mst_allocate_vcpi(&radeon_connector->mst_port->mst_mgr,
 					       radeon_connector->port,
-					       mst_enc->pbn, &slots);
+					       mst_enc->pbn, slots);
 		ret = drm_dp_update_payload_part1(&radeon_connector->mst_port->mst_mgr);
 
 		radeon_dp_mst_set_be_cntl(primary, mst_enc,

include/drm/drm_dp_mst_helper.h

@@ -567,7 +567,8 @@ struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_
 int drm_dp_calc_pbn_mode(int clock, int bpp);
 
 
-bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port, int pbn, int *slots);
+bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
+			      struct drm_dp_mst_port *port, int pbn, int slots);
 
 int drm_dp_mst_get_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port);