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drm/dp: complete the implementation for remote dpcd read

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Current DP MST topology layer has incomplete implementation
for drm_dp_send_dpcd_read function. This change completes
the implementation in order to make it ready for exporting
the function to the dp mst drivers.

Change-Id: I59ce468d0353dab54b37bee7d6917d15cad16020
Signed-off-by: Govinda Rajulu Chenna <gchenna@codeaurora.org>
Signed-off-by: Tatenda Chipeperekwa <tatendac@codeaurora.org>
This commit is contained in:
Govinda Rajulu Chenna 2018-12-18 08:54:14 -05:00 committed by Tatenda Chipeperekwa
parent 9ba5ace1ec
commit 3723400e5b
1 changed files with 42 additions and 6 deletions
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48
drivers/gpu/drm/drm_dp_mst_topology.c
View file

@ -1985,21 +1985,57 @@ EXPORT_SYMBOL(drm_dp_update_payload_part2);
#if 0 /* unused as of yet */
static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr,
struct drm_dp_mst_port *port,
int offset, int size)
int offset, int size, u8 *bytes)
{
int len;
int ret;
struct drm_dp_sideband_msg_tx *txmsg;
struct drm_dp_mst_branch *mstb;
memset(bytes, 0, size);
mstb = drm_dp_get_validated_mstb_ref(mgr, port->parent);
if (!mstb)
return -EINVAL;
txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
if (!txmsg)
return -ENOMEM;
if (!txmsg) {
ret = -ENOMEM;
goto fail_put;
}
len = build_dpcd_read(txmsg, port->port_num, 0, 8);
txmsg->dst = port->parent;
len = build_dpcd_read(txmsg, port->port_num, offset, size);
txmsg->dst = mstb;
drm_dp_queue_down_tx(mgr, txmsg);
ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
if (ret <= 0) {
DRM_ERROR("dpcd read failed\n");
goto fail_free_msg;
}
return 0;
if (txmsg->reply.reply_type == 1) {
DRM_ERROR("dpcd read nack received\n");
ret = -EINVAL;
goto fail_free_msg;
}
if (port->port_num != txmsg->reply.u.remote_dpcd_read_ack.port_number) {
DRM_ERROR("got incorrect port in response\n");
ret = -EINVAL;
goto fail_free_msg;
}
if (size > txmsg->reply.u.remote_dpcd_read_ack.num_bytes)
size = txmsg->reply.u.remote_dpcd_read_ack.num_bytes;
memcpy(bytes, txmsg->reply.u.remote_dpcd_read_ack.bytes, size);
fail_free_msg:
kfree(txmsg);
fail_put:
drm_dp_put_mst_branch_device(mstb);
return ret;
}
#endif