[Intel-gfx] [PATCH v2] drm/dp/mst: Sideband message transaction to power up/down nodes

[Pandiyan, Dhinakaran]

On Thu, 2017-09-07 at 14:04 -0400, Lyude Paul wrote:
> Looks good to me.
> 
> Reviewed-by: Lyude Paul <lyude at redhat.com>
> 


Thanks for the review.
-DK


> On Wed, 2017-09-06 at 17:14 -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.
> > 
> > v2: Fix memory leak (Lyude)
> > Cc: Lyude <lyude at redhat.com>
> > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > Cc: Harry Wentland <harry.wentland at amd.com>
> > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> > ---
> >  drivers/gpu/drm/drm_dp_mst_topology.c | 75
> > +++++++++++++++++++++++++++++++++++
> >  include/drm/drm_dp_mst_helper.h       |  2 +
> >  2 files changed, 77 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> > b/drivers/gpu/drm/drm_dp_mst_topology.c
> > index 41b492f99955..9bc5049e7e59 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 +1765,40 @@ 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;
> > +
> > +	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 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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