On Tue, 2017-09-05 at 18:26 -0700, Dhinakaran Pandiyan wrote:
> 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.
>
> Cc: Lyude <lyude@xxxxxxxxxx>
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Harry Wentland <harry.wentland@xxxxxxx>
> Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
> ---
> drivers/gpu/drm/drm_dp_mst_topology.c | 73
> +++++++++++++++++++++++++++++++++++
> include/drm/drm_dp_mst_helper.h | 2 +
> 2 files changed, 75 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> b/drivers/gpu/drm/drm_dp_mst_topology.c
> index 41b492f99955..a9f12708a046 100644
> --- 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 +544,22 @@ static bool
> drm_dp_sideband_parse_query_payload_ack(struct drm_dp_sideband_msg_r
> 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 +589,9 @@ 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 +718,22 @@ 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 +1765,38 @@ static int drm_dp_payload_send_msg(struct
> drm_dp_mst_topology_mgr *mgr,
> 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;
> +
> + txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
> + if (!txmsg)
> + return -ENOMEM;
> +
> + port = drm_dp_get_validated_port_ref(mgr, port);
> + if (!port)
> + return -EINVAL;
if (!port), then you leak memory by not freeing txmsg
> +
> + 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 0;
> +}
> +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 d55abb75f29a..7f78d26a0766 100644
> --- 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
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