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

[Pandiyan, Dhinakaran]

On Mon, 2017-09-11 at 16:33 +0300, Ville Syrjälä wrote:
> On Wed, Sep 06, 2017 at 05:14:58PM -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.
> 
> I was a bit worried how this handles multiple streams going through
> the same MST device, but looks like the spec has accounted for this
> by having the device skip the D3 if any active streams are present.
> 
> I guess that also means we have to do this after we've turned off the
> stream, assuming we want things actually reach D3. Looks like that does
> match our current order of things.
> 
> Pushed this one to drm-misc-next. Thanks for the patch and review.
> 
Thanks, do you see any potential problems patch with Patch 2/2?
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Re: [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 
> 


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 
> > Cc: Ville Syrjälä 
> > Cc: Harry Wentland 
> > Signed-off-by: Dhinakaran Pandiyan 
> > ---
> >  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([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(, 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 =