drm/dp/mst: Sideband message transaction to power up/down nodes

The POWER_DOWN_PHY and POWER_UP_PHY sideband message transactions allow
the source to reqest any node in a mst path or a whole path to be
powered down or up. This allows drivers to target a specific sink in the
MST topology, an improvement over just power managing the imediate
downstream device. Secondly, since the request-reply protocol waits for an
ACK, we can be sure that a downstream sink has enough time to respond to a
power up/down request.

v2: Fix memory leak (Lyude)
Cc: Lyude <lyude@redhat.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170907001458.9399-1-dhinakaran.pandiyan@intel.com
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 41b492f99955f8d6778197e7102c854e41530b8f..70dcfa58d3c22bb7156c6ecc1b41dc602ec198ba 100644 (file)
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -294,6 +294,12 @@ static void drm_dp_encode_sideband_req(struct drm_dp_sideband_msg_req_body *req,
                memcpy(&buf[idx], req->u.i2c_write.bytes, req->u.i2c_write.num_bytes);
                idx += req->u.i2c_write.num_bytes;
                break;
+
+       case DP_POWER_DOWN_PHY:
+       case DP_POWER_UP_PHY:
+               buf[idx] = (req->u.port_num.port_number & 0xf) << 4;
+               idx++;
+               break;
        }
        raw->cur_len = idx;
 }
@@ -538,6 +544,21 @@ fail_len:
        return false;
 }
 
+static bool drm_dp_sideband_parse_power_updown_phy_ack(struct drm_dp_sideband_msg_rx *raw,
+                                                      struct drm_dp_sideband_msg_reply_body *repmsg)
+{
+       int idx = 1;
+
+       repmsg->u.port_number.port_number = (raw->msg[idx] >> 4) & 0xf;
+       idx++;
+       if (idx > raw->curlen) {
+               DRM_DEBUG_KMS("power up/down phy parse length fail %d %d\n",
+                             idx, raw->curlen);
+               return false;
+       }
+       return true;
+}
+
 static bool drm_dp_sideband_parse_reply(struct drm_dp_sideband_msg_rx *raw,
                                        struct drm_dp_sideband_msg_reply_body *msg)
 {
@@ -567,6 +588,9 @@ static bool drm_dp_sideband_parse_reply(struct drm_dp_sideband_msg_rx *raw,
                return drm_dp_sideband_parse_enum_path_resources_ack(raw, msg);
        case DP_ALLOCATE_PAYLOAD:
                return drm_dp_sideband_parse_allocate_payload_ack(raw, msg);
+       case DP_POWER_DOWN_PHY:
+       case DP_POWER_UP_PHY:
+               return drm_dp_sideband_parse_power_updown_phy_ack(raw, msg);
        default:
                DRM_ERROR("Got unknown reply 0x%02x\n", msg->req_type);
                return false;
@@ -693,6 +717,22 @@ static int build_allocate_payload(struct drm_dp_sideband_msg_tx *msg, int port_n
        return 0;
 }
 
+static int build_power_updown_phy(struct drm_dp_sideband_msg_tx *msg,
+                                 int port_num, bool power_up)
+{
+       struct drm_dp_sideband_msg_req_body req;
+
+       if (power_up)
+               req.req_type = DP_POWER_UP_PHY;
+       else
+               req.req_type = DP_POWER_DOWN_PHY;
+
+       req.u.port_num.port_number = port_num;
+       drm_dp_encode_sideband_req(&req, msg);
+       msg->path_msg = true;
+       return 0;
+}
+
 static int drm_dp_mst_assign_payload_id(struct drm_dp_mst_topology_mgr *mgr,
                                        struct drm_dp_vcpi *vcpi)
 {
@@ -1724,6 +1764,40 @@ fail_put:
        return ret;
 }
 
+int drm_dp_send_power_updown_phy(struct drm_dp_mst_topology_mgr *mgr,
+                                struct drm_dp_mst_port *port, bool power_up)
+{
+       struct drm_dp_sideband_msg_tx *txmsg;
+       int len, ret;
+
+       port = drm_dp_get_validated_port_ref(mgr, port);
+       if (!port)
+               return -EINVAL;
+
+       txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
+       if (!txmsg) {
+               drm_dp_put_port(port);
+               return -ENOMEM;
+       }
+
+       txmsg->dst = port->parent;
+       len = build_power_updown_phy(txmsg, port->port_num, power_up);
+       drm_dp_queue_down_tx(mgr, txmsg);
+
+       ret = drm_dp_mst_wait_tx_reply(port->parent, txmsg);
+       if (ret > 0) {
+               if (txmsg->reply.reply_type == 1)
+                       ret = -EINVAL;
+               else
+                       ret = 0;
+       }
+       kfree(txmsg);
+       drm_dp_put_port(port);
+
+       return ret;
+}
+EXPORT_SYMBOL(drm_dp_send_power_updown_phy);
+
 static int drm_dp_create_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
                                       int id,
                                       struct drm_dp_payload *payload)

diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index d55abb75f29ae1f998a8cc3f0124bacfceb10170..7f78d26a076694ce5dcd42fe99da555fe092daa1 100644 (file)
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -631,5 +631,7 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 int drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
                                     struct drm_dp_mst_topology_mgr *mgr,
                                     int slots);
+int drm_dp_send_power_updown_phy(struct drm_dp_mst_topology_mgr *mgr,
+                                struct drm_dp_mst_port *port, bool power_up);
 
 #endif