Re: [PATCH v5] drm/dp_mst: Fix W=1 warnings

Mostly looks good, some comments below:

On Fri, 2020-01-31 at 11:01 +0100, Benjamin Gaignard wrote:

Fix the warnings that show up with W=1. They are all about unused but set variables. If functions returns are not used anymore make them void.

Signed-off-by: Benjamin Gaignard benjamin.gaignard@st.com

version 5:

• fix indentation

version 4:

• do not touch crc4 unused variable in this patch

CC: lyude@redhat.com CC: airlied@linux.ie CC: jani.nikula@linux.intel.com

drivers/gpu/drm/drm_dp_mst_topology.c | 92 +++++++++++++++-----------------

1 file changed, 40 insertions(+), 52 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index 4104f15f4594..822d2f177f90 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -1034,7 +1034,8 @@ static bool drm_dp_sideband_parse_req(struct drm_dp_sideband_msg_rx *raw, } }

-static int build_dpcd_write(struct drm_dp_sideband_msg_tx *msg, u8 port_num, u32 offset, u8 num_bytes, u8 *bytes) +static void build_dpcd_write(struct drm_dp_sideband_msg_tx *msg,

• 	     u8 port_num, u32 offset, u8 num_bytes, u8 *bytes)
  

{ struct drm_dp_sideband_msg_req_body req;

@@ -1044,17 +1045,14 @@ static int build_dpcd_write(struct drm_dp_sideband_msg_tx *msg, u8 port_num, u32 req.u.dpcd_write.num_bytes = num_bytes; req.u.dpcd_write.bytes = bytes; drm_dp_encode_sideband_req(&req, msg);

• return 0;

}

-static int build_link_address(struct drm_dp_sideband_msg_tx *msg) +static void build_link_address(struct drm_dp_sideband_msg_tx *msg) { struct drm_dp_sideband_msg_req_body req;

req.req_type = DP_LINK_ADDRESS; drm_dp_encode_sideband_req(&req, msg);

• return 0;

}

static int build_clear_payload_id_table(struct drm_dp_sideband_msg_tx *msg) @@ -1066,7 +1064,8 @@ static int build_clear_payload_id_table(struct drm_dp_sideband_msg_tx *msg) return 0; }

-static int build_enum_path_resources(struct drm_dp_sideband_msg_tx *msg, int port_num) +static int build_enum_path_resources(struct drm_dp_sideband_msg_tx *msg,

• 		     int port_num)
  

{ struct drm_dp_sideband_msg_req_body req;

@@ -1077,10 +1076,11 @@ static int build_enum_path_resources(struct drm_dp_sideband_msg_tx *msg, int por return 0; }

-static int build_allocate_payload(struct drm_dp_sideband_msg_tx *msg, int port_num,

• 		  u8 vcpi, uint16_t pbn,
  

• 		  u8 number_sdp_streams,
  

• 		  u8 *sdp_stream_sink)
  

+static void build_allocate_payload(struct drm_dp_sideband_msg_tx *msg,

• 		   int port_num,
  

• 		   u8 vcpi, uint16_t pbn,
  

• 		   u8 number_sdp_streams,
  

• 		   u8 *sdp_stream_sink)
  

{ struct drm_dp_sideband_msg_req_body req; memset(&req, 0, sizeof(req)); @@ -1093,11 +1093,10 @@ static int build_allocate_payload(struct drm_dp_sideband_msg_tx *msg, int port_n number_sdp_streams); drm_dp_encode_sideband_req(&req, msg); msg->path_msg = true;

• return 0;

}

-static int build_power_updown_phy(struct drm_dp_sideband_msg_tx *msg,

• 		  int port_num, bool power_up)
  

+static void 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;

@@ -1109,7 +1108,6 @@ static int build_power_updown_phy(struct drm_dp_sideband_msg_tx *msg, 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, @@ -2054,25 +2052,20 @@ ssize_t drm_dp_mst_dpcd_write(struct drm_dp_aux *aux,

static void drm_dp_check_mstb_guid(struct drm_dp_mst_branch *mstb, u8 *guid) {

• int ret;

• memcpy(mstb->guid, guid, 16);

  if (!drm_dp_validate_guid(mstb->mgr, mstb->guid)) { if (mstb->port_parent) {

• 	ret = drm_dp_send_dpcd_write(
  

• 			mstb->mgr,
  

• 			mstb->port_parent,
  

• 			DP_GUID,
  

• 			16,
  

• 			mstb->guid);
  

• 	drm_dp_send_dpcd_write(mstb->mgr,
  

• 			       mstb->port_parent,
  

• 			       DP_GUID,
  

• 			       16,
  

• 			       mstb->guid);
  

  } else {

• 	ret = drm_dp_dpcd_write(
  

• 			mstb->mgr->aux,
  

• 			DP_GUID,
  

• 			mstb->guid,
  

• 			16);
  

• 	drm_dp_dpcd_write(mstb->mgr->aux,
  

• 			  DP_GUID,
  

• 			  mstb->guid,
  

• 			  16);
  

  }

I think this one we should actually pass the return code from drm_dp_dpcd_write() back from drm_dp_check_mstb_guid(), and then check the return code in any places where we're calling this, instead of just dropping it.

} } @@ -2595,7 +2588,8 @@ static bool drm_dp_validate_guid(struct drm_dp_mst_topology_mgr *mgr, return false; }

-static int build_dpcd_read(struct drm_dp_sideband_msg_tx *msg, u8 port_num, u32 offset, u8 num_bytes) +static void build_dpcd_read(struct drm_dp_sideband_msg_tx *msg,

• 	    u8 port_num, u32 offset, u8 num_bytes)
  

{ struct drm_dp_sideband_msg_req_body req;

@@ -2604,8 +2598,6 @@ static int build_dpcd_read(struct drm_dp_sideband_msg_tx *msg, u8 port_num, u32 req.u.dpcd_read.dpcd_address = offset; req.u.dpcd_read.num_bytes = num_bytes; drm_dp_encode_sideband_req(&req, msg);

• return 0;

}

static int drm_dp_send_sideband_msg(struct drm_dp_mst_topology_mgr *mgr, @@ -2828,7 +2820,7 @@ static int drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_sideband_msg_tx *txmsg; struct drm_dp_link_address_ack_reply *reply; struct drm_dp_mst_port *port, *tmp;

• int i, len, ret, port_mask = 0;

• int i, ret, port_mask = 0; bool changed = false;

  txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);

@@ -2836,7 +2828,7 @@ static int drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr, return -ENOMEM;

txmsg->dst = mstb;

• len = build_link_address(txmsg);

• build_link_address(txmsg);

  mstb->link_address_sent = true; drm_dp_queue_down_tx(mgr, txmsg);

@@ -2898,14 +2890,14 @@ void drm_dp_send_clear_payload_id_table(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_branch *mstb) { struct drm_dp_sideband_msg_tx *txmsg;

• int len, ret;

• int ret;

  txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL); if (!txmsg) return;

  txmsg->dst = mstb;

• len = build_clear_payload_id_table(txmsg);

• build_clear_payload_id_table(txmsg);

  drm_dp_queue_down_tx(mgr, txmsg);

@@ -2923,7 +2915,6 @@ drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr, { struct drm_dp_enum_path_resources_ack_reply *path_res; struct drm_dp_sideband_msg_tx *txmsg;

• int len; int ret;

  txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);

@@ -2931,7 +2922,7 @@ drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr, return -ENOMEM;

txmsg->dst = mstb;

• len = build_enum_path_resources(txmsg, port->port_num);

• build_enum_path_resources(txmsg, port->port_num);

  drm_dp_queue_down_tx(mgr, txmsg);

@@ -3014,7 +3005,7 @@ static int drm_dp_payload_send_msg(struct drm_dp_mst_topology_mgr *mgr, { struct drm_dp_sideband_msg_tx *txmsg; struct drm_dp_mst_branch *mstb;

• int len, ret, port_num;

• int ret, port_num; u8 sinks[DRM_DP_MAX_SDP_STREAMS]; int i;

@@ -3039,9 +3030,9 @@ static int drm_dp_payload_send_msg(struct drm_dp_mst_topology_mgr *mgr, sinks[i] = i;

txmsg->dst = mstb;

• len = build_allocate_payload(txmsg, port_num,

• 		     id,
  

• 		     pbn, port->num_sdp_streams, sinks);
  

• build_allocate_payload(txmsg, port_num,

• 	       id,
  

• 	       pbn, port->num_sdp_streams, sinks);
  
  

  drm_dp_queue_down_tx(mgr, txmsg);

@@ -3070,7 +3061,7 @@ 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;

• int ret;

  port = drm_dp_mst_topology_get_port_validated(mgr, port); if (!port)

@@ -3083,7 +3074,7 @@ int drm_dp_send_power_updown_phy(struct drm_dp_mst_topology_mgr *mgr, }

txmsg->dst = port->parent;

• len = build_power_updown_phy(txmsg, port->port_num, power_up);

• 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);

@@ -3305,7 +3296,6 @@ static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port, int offset, int size, u8 *bytes) {

• int len; int ret = 0; struct drm_dp_sideband_msg_tx *txmsg; struct drm_dp_mst_branch *mstb;

@@ -3320,7 +3310,7 @@ static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr, goto fail_put; }

• len = build_dpcd_read(txmsg, port->port_num, offset, size);

• build_dpcd_read(txmsg, port->port_num, offset, size); txmsg->dst = port->parent;

  drm_dp_queue_down_tx(mgr, txmsg);

@@ -3358,7 +3348,6 @@ static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port, int offset, int size, u8 *bytes) {

• int len; int ret; struct drm_dp_sideband_msg_tx *txmsg; struct drm_dp_mst_branch *mstb;

@@ -3373,7 +3362,7 @@ static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr, goto fail_put; }

• len = build_dpcd_write(txmsg, port->port_num, offset, size, bytes);

• build_dpcd_write(txmsg, port->port_num, offset, size, bytes); txmsg->dst = mstb;

  drm_dp_queue_down_tx(mgr, txmsg);

@@ -4529,17 +4518,16 @@ void drm_dp_mst_dump_topology(struct seq_file *m, mutex_lock(&mgr->lock); if (mgr->mst_primary) { u8 buf[DP_PAYLOAD_TABLE_SIZE];

• int ret;
  
  

• ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, buf,
  

DP_RECEIVER_CAP_SIZE);

• drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, buf,
  

DP_RECEIVER_CAP_SIZE); seq_printf(m, "dpcd: %*ph\n", DP_RECEIVER_CAP_SIZE, buf);

• ret = drm_dp_dpcd_read(mgr->aux, DP_FAUX_CAP, buf, 2);
  

• drm_dp_dpcd_read(mgr->aux, DP_FAUX_CAP, buf, 2);
  

  seq_printf(m, "faux/mst: %*ph\n", 2, buf);

• ret = drm_dp_dpcd_read(mgr->aux, DP_MSTM_CTRL, buf, 1);
  

• drm_dp_dpcd_read(mgr->aux, DP_MSTM_CTRL, buf, 1);
  

  seq_printf(m, "mst ctrl: %*ph\n", 1, buf);

Same for this one, would be better to maybe return with an error code or make it obvious in the seq_printf() output that the drm_dp_dpcd_read() calls failed since otherwise we might just end up printing out garbage.

With those two changed and split into separate patches, this patch is:

Reviewed-by: Lyude Paul lyude@redhat.com

/* dump the standard OUI branch header */

• ret = drm_dp_dpcd_read(mgr->aux, DP_BRANCH_OUI, buf,
  

DP_BRANCH_OUI_HEADER_SIZE);

• drm_dp_dpcd_read(mgr->aux, DP_BRANCH_OUI, buf,
  

DP_BRANCH_OUI_HEADER_SIZE); seq_printf(m, "branch oui: %*phN devid: ", 3, buf); for (i = 0x3; i < 0x8 && buf[i]; i++) seq_printf(m, "%c", buf[i]);