diff mbox series

[v5,1/3] drm/dp_mst: Add self-tests for up requests

Message ID 20210525105913.v5.1.I6f50a7996687318ba298c24a3663c8be7dd432c7@changeid (mailing list archive)
State New, archived
Headers show
Series [v5,1/3] drm/dp_mst: Add self-tests for up requests | expand

Commit Message

Sam McNally May 25, 2021, 12:59 a.m. UTC
Up requests are decoded by drm_dp_sideband_parse_req(), which operates
on a drm_dp_sideband_msg_rx, unlike down requests. Expand the existing
self-test helper sideband_msg_req_encode_decode() to copy the message
contents and length from a drm_dp_sideband_msg_tx to
drm_dp_sideband_msg_rx and use the parse function under test in place of
decode. Add an additional helper for testing clearly-invalid up
messages, verifying that parse rejects them.

Add support for currently-supported up requests to
drm_dp_dump_sideband_msg_req_body(); add support to
drm_dp_encode_sideband_req() to allow encoding for the self-tests.

Add self-tests for CONNECTION_STATUS_NOTIFY and RESOURCE_STATUS_NOTIFY.

Signed-off-by: Sam McNally <sammc@chromium.org>
---

Changes in v5:
- Set mock device name to more clearly attribute error/debug logging to
  the self-test, in particular for cases where failures are expected

Changes in v4:
- New in v4

 drivers/gpu/drm/drm_dp_mst_topology.c         |  54 ++++++-
 .../gpu/drm/drm_dp_mst_topology_internal.h    |   4 +
 .../drm/selftests/test-drm_dp_mst_helper.c    | 149 ++++++++++++++++--
 3 files changed, 192 insertions(+), 15 deletions(-)

Comments

Lyude Paul May 27, 2021, 8:08 p.m. UTC | #1
On Tue, 2021-05-25 at 10:59 +1000, Sam McNally wrote:
> Up requests are decoded by drm_dp_sideband_parse_req(), which operates
> on a drm_dp_sideband_msg_rx, unlike down requests. Expand the existing
> self-test helper sideband_msg_req_encode_decode() to copy the message
> contents and length from a drm_dp_sideband_msg_tx to
> drm_dp_sideband_msg_rx and use the parse function under test in place of
> decode. Add an additional helper for testing clearly-invalid up
> messages, verifying that parse rejects them.
> 
> Add support for currently-supported up requests to
> drm_dp_dump_sideband_msg_req_body(); add support to
> drm_dp_encode_sideband_req() to allow encoding for the self-tests.
> 
> Add self-tests for CONNECTION_STATUS_NOTIFY and RESOURCE_STATUS_NOTIFY.
> 
> Signed-off-by: Sam McNally <sammc@chromium.org>
> ---
> 
> Changes in v5:
> - Set mock device name to more clearly attribute error/debug logging to
>   the self-test, in particular for cases where failures are expected
> 
> Changes in v4:
> - New in v4
> 
>  drivers/gpu/drm/drm_dp_mst_topology.c         |  54 ++++++-
>  .../gpu/drm/drm_dp_mst_topology_internal.h    |   4 +
>  .../drm/selftests/test-drm_dp_mst_helper.c    | 149 ++++++++++++++++--
>  3 files changed, 192 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> b/drivers/gpu/drm/drm_dp_mst_topology.c
> index 54604633e65c..573f39a3dc16 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -442,6 +442,37 @@ drm_dp_encode_sideband_req(const struct
> drm_dp_sideband_msg_req_body *req,
>                 idx++;
>                 }
>                 break;
> +       case DP_CONNECTION_STATUS_NOTIFY: {
> +               const struct drm_dp_connection_status_notify *msg;
> +
> +               msg = &req->u.conn_stat;
> +               buf[idx] = (msg->port_number & 0xf) << 4;
> +               idx++;
> +               memcpy(&raw->msg[idx], msg->guid, 16);
> +               idx += 16;
> +               raw->msg[idx] = 0;
> +               raw->msg[idx] |= msg->legacy_device_plug_status ? BIT(6) :
> 0;
> +               raw->msg[idx] |= msg->displayport_device_plug_status ?
> BIT(5) : 0;
> +               raw->msg[idx] |= msg->message_capability_status ? BIT(4) :
> 0;
> +               raw->msg[idx] |= msg->input_port ? BIT(3) : 0;
> +               raw->msg[idx] |= FIELD_PREP(GENMASK(2, 0), msg-
> >peer_device_type);
> +               idx++;
> +               break;
> +       }
> +       case DP_RESOURCE_STATUS_NOTIFY: {
> +               const struct drm_dp_resource_status_notify *msg;
> +
> +               msg = &req->u.resource_stat;
> +               buf[idx] = (msg->port_number & 0xf) << 4;
> +               idx++;
> +               memcpy(&raw->msg[idx], msg->guid, 16);
> +               idx += 16;
> +               buf[idx] = (msg->available_pbn & 0xff00) >> 8;
> +               idx++;
> +               buf[idx] = (msg->available_pbn & 0xff);
> +               idx++;
> +               break;
> +       }
>         }
>         raw->cur_len = idx;
>  }
> @@ -672,6 +703,22 @@ drm_dp_dump_sideband_msg_req_body(const struct
> drm_dp_sideband_msg_req_body *req
>                   req->u.enc_status.stream_behavior,
>                   req->u.enc_status.valid_stream_behavior);
>                 break;
> +       case DP_CONNECTION_STATUS_NOTIFY:
> +               P("port=%d guid=%*ph legacy=%d displayport=%d messaging=%d
> input=%d peer_type=%d",
> +                 req->u.conn_stat.port_number,
> +                 (int)ARRAY_SIZE(req->u.conn_stat.guid), req-
> >u.conn_stat.guid,
> +                 req->u.conn_stat.legacy_device_plug_status,
> +                 req->u.conn_stat.displayport_device_plug_status,
> +                 req->u.conn_stat.message_capability_status,
> +                 req->u.conn_stat.input_port,
> +                 req->u.conn_stat.peer_device_type);
> +               break;
> +       case DP_RESOURCE_STATUS_NOTIFY:
> +               P("port=%d guid=%*ph pbn=%d",
> +                 req->u.resource_stat.port_number,
> +                 (int)ARRAY_SIZE(req->u.resource_stat.guid), req-
> >u.resource_stat.guid,
> +                 req->u.resource_stat.available_pbn);
> +               break;
>         default:
>                 P("???\n");
>                 break;
> @@ -1116,9 +1163,9 @@ static bool
> drm_dp_sideband_parse_resource_status_notify(const struct drm_dp_mst
>         return false;
>  }
>  
> -static bool drm_dp_sideband_parse_req(const struct drm_dp_mst_topology_mgr
> *mgr,
> -                                     struct drm_dp_sideband_msg_rx *raw,
> -                                     struct drm_dp_sideband_msg_req_body
> *msg)
> +bool drm_dp_sideband_parse_req(const struct drm_dp_mst_topology_mgr *mgr,
> +                              struct drm_dp_sideband_msg_rx *raw,
> +                              struct drm_dp_sideband_msg_req_body *msg)
>  {
>         memset(msg, 0, sizeof(*msg));
>         msg->req_type = (raw->msg[0] & 0x7f);
> @@ -1134,6 +1181,7 @@ static bool drm_dp_sideband_parse_req(const struct
> drm_dp_mst_topology_mgr *mgr,
>                 return false;
>         }
>  }
> +EXPORT_SYMBOL_FOR_TESTS_ONLY(drm_dp_sideband_parse_req);
>  
>  static void build_dpcd_write(struct drm_dp_sideband_msg_tx *msg,
>                              u8 port_num, u32 offset, u8 num_bytes, u8
> *bytes)
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology_internal.h
> b/drivers/gpu/drm/drm_dp_mst_topology_internal.h
> index eeda9a61c657..0356a2e0dba1 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology_internal.h
> +++ b/drivers/gpu/drm/drm_dp_mst_topology_internal.h
> @@ -21,4 +21,8 @@ void
>  drm_dp_dump_sideband_msg_req_body(const struct drm_dp_sideband_msg_req_body
> *req,
>                                   int indent, struct drm_printer *printer);
>  
> +bool
> +drm_dp_sideband_parse_req(const struct drm_dp_mst_topology_mgr *mgr,
> +                         struct drm_dp_sideband_msg_rx *raw,
> +                         struct drm_dp_sideband_msg_req_body *msg);
>  #endif /* !_DRM_DP_MST_HELPER_INTERNAL_H_ */
> diff --git a/drivers/gpu/drm/selftests/test-drm_dp_mst_helper.c
> b/drivers/gpu/drm/selftests/test-drm_dp_mst_helper.c
> index 6b4759ed6bfd..7bbeb1e5bc97 100644
> --- a/drivers/gpu/drm/selftests/test-drm_dp_mst_helper.c
> +++ b/drivers/gpu/drm/selftests/test-drm_dp_mst_helper.c
> @@ -13,6 +13,10 @@
>  #include "../drm_dp_mst_topology_internal.h"
>  #include "test-drm_modeset_common.h"
>  
> +static void mock_release(struct device *dev)
> +{
> +}
> +
>  int igt_dp_mst_calc_pbn_mode(void *ignored)
>  {
>         int pbn, i;
> @@ -120,27 +124,60 @@ sideband_msg_req_equal(const struct
> drm_dp_sideband_msg_req_body *in,
>  static bool
>  sideband_msg_req_encode_decode(struct drm_dp_sideband_msg_req_body *in)
>  {
> -       struct drm_dp_sideband_msg_req_body *out;
> +       struct drm_dp_sideband_msg_req_body *out = NULL;
>         struct drm_printer p = drm_err_printer(PREFIX_STR);
> -       struct drm_dp_sideband_msg_tx *txmsg;
> +       struct drm_dp_sideband_msg_tx *txmsg = NULL;
> +       struct drm_dp_sideband_msg_rx *rxmsg = NULL;
> +       struct drm_dp_mst_topology_mgr *mgr = NULL;
>         int i, ret;
> -       bool result = true;
> +       bool result = false;
>  
>         out = kzalloc(sizeof(*out), GFP_KERNEL);
>         if (!out)
> -               return false;
> +               goto out;
>  
>         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
>         if (!txmsg)
> -               return false;
> +               goto out;
>  
> -       drm_dp_encode_sideband_req(in, txmsg);
> -       ret = drm_dp_decode_sideband_req(txmsg, out);
> -       if (ret < 0) {
> -               drm_printf(&p, "Failed to decode sideband request: %d\n",
> -                          ret);
> -               result = false;
> +       rxmsg = kzalloc(sizeof(*rxmsg), GFP_KERNEL);
> +       if (!rxmsg)
>                 goto out;
> +
> +       mgr = kzalloc(sizeof(*mgr), GFP_KERNEL);
> +       if (!mgr)
> +               goto out;
> +
> +       mgr->dev = kzalloc(sizeof(*mgr->dev), GFP_KERNEL);
> +       if (!mgr->dev)
> +               goto out;
> +
> +       mgr->dev->dev = kzalloc(sizeof(*mgr->dev->dev), GFP_KERNEL);
> +       if (!mgr->dev->dev)
> +               goto out;
> +
> +       mgr->dev->dev->release = mock_release;
> +       mgr->dev->dev->init_name = PREFIX_STR;
> +       device_initialize(mgr->dev->dev);
> +
> +       drm_dp_encode_sideband_req(in, txmsg);
> +       switch (in->req_type) {
> +       case DP_CONNECTION_STATUS_NOTIFY:
> +       case DP_RESOURCE_STATUS_NOTIFY:
> +               memcpy(&rxmsg->msg, txmsg->msg, ARRAY_SIZE(rxmsg->msg));
> +               rxmsg->curlen = txmsg->cur_len;
> +               if (!drm_dp_sideband_parse_req(mgr, rxmsg, out)) {
> +                       drm_printf(&p, "Failed to decode sideband
> request\n");
> +                       goto out;
> +               }
> +               break;
> +       default:
> +               ret = drm_dp_decode_sideband_req(txmsg, out);
> +               if (ret < 0) {
> +                       drm_printf(&p, "Failed to decode sideband request:
> %d\n", ret);
> +                       goto out;
> +               }
> +               break;
>         }
>  
>         if (!sideband_msg_req_equal(in, out)) {
> @@ -148,9 +185,9 @@ sideband_msg_req_encode_decode(struct
> drm_dp_sideband_msg_req_body *in)
>                 drm_dp_dump_sideband_msg_req_body(in, 1, &p);
>                 drm_printf(&p, "Got:\n");
>                 drm_dp_dump_sideband_msg_req_body(out, 1, &p);
> -               result = false;
>                 goto out;
>         }
> +       result = true;
>  
>         switch (in->req_type) {
>         case DP_REMOTE_DPCD_WRITE:
> @@ -171,6 +208,66 @@ sideband_msg_req_encode_decode(struct
> drm_dp_sideband_msg_req_body *in)
>  out:
>         kfree(out);
>         kfree(txmsg);
> +       kfree(rxmsg);
> +       if (mgr) {
> +               if (mgr->dev) {
> +                       put_device(mgr->dev->dev);
> +                       kfree(mgr->dev);
> +               }
> +               kfree(mgr);
> +       }
> +       return result;
> +}
> +
> +static bool
> +sideband_msg_req_parse(int req_type)
> +{
> +       struct drm_dp_sideband_msg_req_body *out = NULL;
> +       struct drm_printer p = drm_err_printer(PREFIX_STR);
> +       struct drm_dp_sideband_msg_rx *rxmsg = NULL;
> +       struct drm_dp_mst_topology_mgr *mgr = NULL;
> +       bool result = false;
> +
> +       out = kzalloc(sizeof(*out), GFP_KERNEL);
> +       if (!out)
> +               goto out;
> +
> +       rxmsg = kzalloc(sizeof(*rxmsg), GFP_KERNEL);
> +       if (!rxmsg)
> +               goto out;
> +
> +       mgr = kzalloc(sizeof(*mgr), GFP_KERNEL);
> +       if (!mgr)
> +               goto out;
> +
> +       mgr->dev = kzalloc(sizeof(*mgr->dev), GFP_KERNEL);
> +       if (!mgr->dev)
> +               goto out;
> +
> +       mgr->dev->dev = kzalloc(sizeof(*mgr->dev->dev), GFP_KERNEL);
> +       if (!mgr->dev->dev)
> +               goto out;
> +
> +       mgr->dev->dev->release = mock_release;
> +       mgr->dev->dev->init_name = PREFIX_STR " expected parse failure";
> +       device_initialize(mgr->dev->dev);
> +
> +       rxmsg->curlen = 1;
> +       rxmsg->msg[0] = req_type & 0x7f;
> +       if (drm_dp_sideband_parse_req(mgr, rxmsg, out))
> +               drm_printf(&p, "Unexpectedly decoded invalid sideband
> request\n");
> +       else
> +               result = true;
> +out:
> +       kfree(out);
> +       kfree(rxmsg);
> +       if (mgr) {
> +               if (mgr->dev) {
> +                       put_device(mgr->dev->dev);
> +                       kfree(mgr->dev);
> +               }
> +               kfree(mgr);
> +       }
>         return result;
>  }
>  
> @@ -268,6 +365,34 @@ int igt_dp_mst_sideband_msg_req_decode(void *unused)
>         in.u.enc_status.valid_stream_behavior = 1;
>         DO_TEST();
>  
> +       in.req_type = DP_CONNECTION_STATUS_NOTIFY;
> +       in.u.conn_stat.port_number = 0xf;
> +       get_random_bytes(in.u.conn_stat.guid, sizeof(in.u.conn_stat.guid));
> +       in.u.conn_stat.legacy_device_plug_status = 1;
> +       in.u.conn_stat.displayport_device_plug_status = 0;
> +       in.u.conn_stat.message_capability_status = 0;
> +       in.u.conn_stat.input_port = 0;
> +       in.u.conn_stat.peer_device_type = 7;
> +       DO_TEST();
> +       in.u.conn_stat.displayport_device_plug_status = 1;
> +       DO_TEST();
> +       in.u.conn_stat.message_capability_status = 1;
> +       DO_TEST();
> +       in.u.conn_stat.input_port = 1;
> +       DO_TEST();
> +
> +       in.req_type = DP_RESOURCE_STATUS_NOTIFY;
> +       in.u.resource_stat.port_number = 0xf;
> +       get_random_bytes(in.u.resource_stat.guid,
> sizeof(in.u.resource_stat.guid));

Do you think you might be up to moving some of the random functions i915 uses
for selftests out of drivers/gpu/drm/i915/selftests/i915_random.h so that we
could use them here and be able to print out the actual seeds being used for
randomness so that failures can be reproduced reliably?

Either way, patches 1-2 are:

Reviewed-by: Lyude Paul <lyude@redhat.com>

Will have the third reviewed in just a moment, there's some tiny nitpicks w/
it

> +       in.u.resource_stat.available_pbn = 0xcdef;
> +       DO_TEST();
> +
> +#undef DO_TEST
> +#define DO_TEST(req_type) FAIL_ON(!sideband_msg_req_parse(req_type))
> +       DO_TEST(DP_CONNECTION_STATUS_NOTIFY);
> +       DO_TEST(DP_RESOURCE_STATUS_NOTIFY);
> +
> +       DO_TEST(DP_REMOTE_I2C_WRITE);
>  #undef DO_TEST
>         return 0;
>  }
diff mbox series

Patch

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 54604633e65c..573f39a3dc16 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -442,6 +442,37 @@  drm_dp_encode_sideband_req(const struct drm_dp_sideband_msg_req_body *req,
 		idx++;
 		}
 		break;
+	case DP_CONNECTION_STATUS_NOTIFY: {
+		const struct drm_dp_connection_status_notify *msg;
+
+		msg = &req->u.conn_stat;
+		buf[idx] = (msg->port_number & 0xf) << 4;
+		idx++;
+		memcpy(&raw->msg[idx], msg->guid, 16);
+		idx += 16;
+		raw->msg[idx] = 0;
+		raw->msg[idx] |= msg->legacy_device_plug_status ? BIT(6) : 0;
+		raw->msg[idx] |= msg->displayport_device_plug_status ? BIT(5) : 0;
+		raw->msg[idx] |= msg->message_capability_status ? BIT(4) : 0;
+		raw->msg[idx] |= msg->input_port ? BIT(3) : 0;
+		raw->msg[idx] |= FIELD_PREP(GENMASK(2, 0), msg->peer_device_type);
+		idx++;
+		break;
+	}
+	case DP_RESOURCE_STATUS_NOTIFY: {
+		const struct drm_dp_resource_status_notify *msg;
+
+		msg = &req->u.resource_stat;
+		buf[idx] = (msg->port_number & 0xf) << 4;
+		idx++;
+		memcpy(&raw->msg[idx], msg->guid, 16);
+		idx += 16;
+		buf[idx] = (msg->available_pbn & 0xff00) >> 8;
+		idx++;
+		buf[idx] = (msg->available_pbn & 0xff);
+		idx++;
+		break;
+	}
 	}
 	raw->cur_len = idx;
 }
@@ -672,6 +703,22 @@  drm_dp_dump_sideband_msg_req_body(const struct drm_dp_sideband_msg_req_body *req
 		  req->u.enc_status.stream_behavior,
 		  req->u.enc_status.valid_stream_behavior);
 		break;
+	case DP_CONNECTION_STATUS_NOTIFY:
+		P("port=%d guid=%*ph legacy=%d displayport=%d messaging=%d input=%d peer_type=%d",
+		  req->u.conn_stat.port_number,
+		  (int)ARRAY_SIZE(req->u.conn_stat.guid), req->u.conn_stat.guid,
+		  req->u.conn_stat.legacy_device_plug_status,
+		  req->u.conn_stat.displayport_device_plug_status,
+		  req->u.conn_stat.message_capability_status,
+		  req->u.conn_stat.input_port,
+		  req->u.conn_stat.peer_device_type);
+		break;
+	case DP_RESOURCE_STATUS_NOTIFY:
+		P("port=%d guid=%*ph pbn=%d",
+		  req->u.resource_stat.port_number,
+		  (int)ARRAY_SIZE(req->u.resource_stat.guid), req->u.resource_stat.guid,
+		  req->u.resource_stat.available_pbn);
+		break;
 	default:
 		P("???\n");
 		break;
@@ -1116,9 +1163,9 @@  static bool drm_dp_sideband_parse_resource_status_notify(const struct drm_dp_mst
 	return false;
 }
 
-static bool drm_dp_sideband_parse_req(const struct drm_dp_mst_topology_mgr *mgr,
-				      struct drm_dp_sideband_msg_rx *raw,
-				      struct drm_dp_sideband_msg_req_body *msg)
+bool drm_dp_sideband_parse_req(const struct drm_dp_mst_topology_mgr *mgr,
+			       struct drm_dp_sideband_msg_rx *raw,
+			       struct drm_dp_sideband_msg_req_body *msg)
 {
 	memset(msg, 0, sizeof(*msg));
 	msg->req_type = (raw->msg[0] & 0x7f);
@@ -1134,6 +1181,7 @@  static bool drm_dp_sideband_parse_req(const struct drm_dp_mst_topology_mgr *mgr,
 		return false;
 	}
 }
+EXPORT_SYMBOL_FOR_TESTS_ONLY(drm_dp_sideband_parse_req);
 
 static void build_dpcd_write(struct drm_dp_sideband_msg_tx *msg,
 			     u8 port_num, u32 offset, u8 num_bytes, u8 *bytes)
diff --git a/drivers/gpu/drm/drm_dp_mst_topology_internal.h b/drivers/gpu/drm/drm_dp_mst_topology_internal.h
index eeda9a61c657..0356a2e0dba1 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology_internal.h
+++ b/drivers/gpu/drm/drm_dp_mst_topology_internal.h
@@ -21,4 +21,8 @@  void
 drm_dp_dump_sideband_msg_req_body(const struct drm_dp_sideband_msg_req_body *req,
 				  int indent, struct drm_printer *printer);
 
+bool
+drm_dp_sideband_parse_req(const struct drm_dp_mst_topology_mgr *mgr,
+			  struct drm_dp_sideband_msg_rx *raw,
+			  struct drm_dp_sideband_msg_req_body *msg);
 #endif /* !_DRM_DP_MST_HELPER_INTERNAL_H_ */
diff --git a/drivers/gpu/drm/selftests/test-drm_dp_mst_helper.c b/drivers/gpu/drm/selftests/test-drm_dp_mst_helper.c
index 6b4759ed6bfd..7bbeb1e5bc97 100644
--- a/drivers/gpu/drm/selftests/test-drm_dp_mst_helper.c
+++ b/drivers/gpu/drm/selftests/test-drm_dp_mst_helper.c
@@ -13,6 +13,10 @@ 
 #include "../drm_dp_mst_topology_internal.h"
 #include "test-drm_modeset_common.h"
 
+static void mock_release(struct device *dev)
+{
+}
+
 int igt_dp_mst_calc_pbn_mode(void *ignored)
 {
 	int pbn, i;
@@ -120,27 +124,60 @@  sideband_msg_req_equal(const struct drm_dp_sideband_msg_req_body *in,
 static bool
 sideband_msg_req_encode_decode(struct drm_dp_sideband_msg_req_body *in)
 {
-	struct drm_dp_sideband_msg_req_body *out;
+	struct drm_dp_sideband_msg_req_body *out = NULL;
 	struct drm_printer p = drm_err_printer(PREFIX_STR);
-	struct drm_dp_sideband_msg_tx *txmsg;
+	struct drm_dp_sideband_msg_tx *txmsg = NULL;
+	struct drm_dp_sideband_msg_rx *rxmsg = NULL;
+	struct drm_dp_mst_topology_mgr *mgr = NULL;
 	int i, ret;
-	bool result = true;
+	bool result = false;
 
 	out = kzalloc(sizeof(*out), GFP_KERNEL);
 	if (!out)
-		return false;
+		goto out;
 
 	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
 	if (!txmsg)
-		return false;
+		goto out;
 
-	drm_dp_encode_sideband_req(in, txmsg);
-	ret = drm_dp_decode_sideband_req(txmsg, out);
-	if (ret < 0) {
-		drm_printf(&p, "Failed to decode sideband request: %d\n",
-			   ret);
-		result = false;
+	rxmsg = kzalloc(sizeof(*rxmsg), GFP_KERNEL);
+	if (!rxmsg)
 		goto out;
+
+	mgr = kzalloc(sizeof(*mgr), GFP_KERNEL);
+	if (!mgr)
+		goto out;
+
+	mgr->dev = kzalloc(sizeof(*mgr->dev), GFP_KERNEL);
+	if (!mgr->dev)
+		goto out;
+
+	mgr->dev->dev = kzalloc(sizeof(*mgr->dev->dev), GFP_KERNEL);
+	if (!mgr->dev->dev)
+		goto out;
+
+	mgr->dev->dev->release = mock_release;
+	mgr->dev->dev->init_name = PREFIX_STR;
+	device_initialize(mgr->dev->dev);
+
+	drm_dp_encode_sideband_req(in, txmsg);
+	switch (in->req_type) {
+	case DP_CONNECTION_STATUS_NOTIFY:
+	case DP_RESOURCE_STATUS_NOTIFY:
+		memcpy(&rxmsg->msg, txmsg->msg, ARRAY_SIZE(rxmsg->msg));
+		rxmsg->curlen = txmsg->cur_len;
+		if (!drm_dp_sideband_parse_req(mgr, rxmsg, out)) {
+			drm_printf(&p, "Failed to decode sideband request\n");
+			goto out;
+		}
+		break;
+	default:
+		ret = drm_dp_decode_sideband_req(txmsg, out);
+		if (ret < 0) {
+			drm_printf(&p, "Failed to decode sideband request: %d\n", ret);
+			goto out;
+		}
+		break;
 	}
 
 	if (!sideband_msg_req_equal(in, out)) {
@@ -148,9 +185,9 @@  sideband_msg_req_encode_decode(struct drm_dp_sideband_msg_req_body *in)
 		drm_dp_dump_sideband_msg_req_body(in, 1, &p);
 		drm_printf(&p, "Got:\n");
 		drm_dp_dump_sideband_msg_req_body(out, 1, &p);
-		result = false;
 		goto out;
 	}
+	result = true;
 
 	switch (in->req_type) {
 	case DP_REMOTE_DPCD_WRITE:
@@ -171,6 +208,66 @@  sideband_msg_req_encode_decode(struct drm_dp_sideband_msg_req_body *in)
 out:
 	kfree(out);
 	kfree(txmsg);
+	kfree(rxmsg);
+	if (mgr) {
+		if (mgr->dev) {
+			put_device(mgr->dev->dev);
+			kfree(mgr->dev);
+		}
+		kfree(mgr);
+	}
+	return result;
+}
+
+static bool
+sideband_msg_req_parse(int req_type)
+{
+	struct drm_dp_sideband_msg_req_body *out = NULL;
+	struct drm_printer p = drm_err_printer(PREFIX_STR);
+	struct drm_dp_sideband_msg_rx *rxmsg = NULL;
+	struct drm_dp_mst_topology_mgr *mgr = NULL;
+	bool result = false;
+
+	out = kzalloc(sizeof(*out), GFP_KERNEL);
+	if (!out)
+		goto out;
+
+	rxmsg = kzalloc(sizeof(*rxmsg), GFP_KERNEL);
+	if (!rxmsg)
+		goto out;
+
+	mgr = kzalloc(sizeof(*mgr), GFP_KERNEL);
+	if (!mgr)
+		goto out;
+
+	mgr->dev = kzalloc(sizeof(*mgr->dev), GFP_KERNEL);
+	if (!mgr->dev)
+		goto out;
+
+	mgr->dev->dev = kzalloc(sizeof(*mgr->dev->dev), GFP_KERNEL);
+	if (!mgr->dev->dev)
+		goto out;
+
+	mgr->dev->dev->release = mock_release;
+	mgr->dev->dev->init_name = PREFIX_STR " expected parse failure";
+	device_initialize(mgr->dev->dev);
+
+	rxmsg->curlen = 1;
+	rxmsg->msg[0] = req_type & 0x7f;
+	if (drm_dp_sideband_parse_req(mgr, rxmsg, out))
+		drm_printf(&p, "Unexpectedly decoded invalid sideband request\n");
+	else
+		result = true;
+out:
+	kfree(out);
+	kfree(rxmsg);
+	if (mgr) {
+		if (mgr->dev) {
+			put_device(mgr->dev->dev);
+			kfree(mgr->dev);
+		}
+		kfree(mgr);
+	}
 	return result;
 }
 
@@ -268,6 +365,34 @@  int igt_dp_mst_sideband_msg_req_decode(void *unused)
 	in.u.enc_status.valid_stream_behavior = 1;
 	DO_TEST();
 
+	in.req_type = DP_CONNECTION_STATUS_NOTIFY;
+	in.u.conn_stat.port_number = 0xf;
+	get_random_bytes(in.u.conn_stat.guid, sizeof(in.u.conn_stat.guid));
+	in.u.conn_stat.legacy_device_plug_status = 1;
+	in.u.conn_stat.displayport_device_plug_status = 0;
+	in.u.conn_stat.message_capability_status = 0;
+	in.u.conn_stat.input_port = 0;
+	in.u.conn_stat.peer_device_type = 7;
+	DO_TEST();
+	in.u.conn_stat.displayport_device_plug_status = 1;
+	DO_TEST();
+	in.u.conn_stat.message_capability_status = 1;
+	DO_TEST();
+	in.u.conn_stat.input_port = 1;
+	DO_TEST();
+
+	in.req_type = DP_RESOURCE_STATUS_NOTIFY;
+	in.u.resource_stat.port_number = 0xf;
+	get_random_bytes(in.u.resource_stat.guid, sizeof(in.u.resource_stat.guid));
+	in.u.resource_stat.available_pbn = 0xcdef;
+	DO_TEST();
+
+#undef DO_TEST
+#define DO_TEST(req_type) FAIL_ON(!sideband_msg_req_parse(req_type))
+	DO_TEST(DP_CONNECTION_STATUS_NOTIFY);
+	DO_TEST(DP_RESOURCE_STATUS_NOTIFY);
+
+	DO_TEST(DP_REMOTE_I2C_WRITE);
 #undef DO_TEST
 	return 0;
 }