drm/amd/display: improve dpia pre-train

[WHY]
We see unstable DP LL 4.2.1.3 test result with dpia pre-train. It is
because the outbox interrupt mechanism can not handle HPD
immediately and require some improvement.

[HOW]
1. not enable link if hpd_pending is true.
2. abort pre-train if training failed and hpd_pending is true.
3. check if 2 lane supported when it is alt mode

Reviewed-by: Wenjing Liu <wenjing.liu@amd.com>
Reviewed-by: Meenakshikumar Somasundaram <meenakshikumar.somasundaram@amd.com>
Signed-off-by: Peichen Huang <PeiChen.Huang@amd.com>
Signed-off-by: Tom Chung <chiahsuan.chung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/dc/dio/dcn31/dcn31_dio_link_encoder.c b/drivers/gpu/drm/amd/display/dc/dio/dcn31/dcn31_dio_link_encoder.c
index b2cea59ba5d49facda28c6898a1bc8ff41d4a1f1..9a92f73d5b7feca1aeaf014ac02d03864bb56ea9 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/dio/dcn31/dcn31_dio_link_encoder.c
+++ b/drivers/gpu/drm/amd/display/dc/dio/dcn31/dcn31_dio_link_encoder.c
@@ -653,8 +653,9 @@ void dcn31_link_encoder_get_max_link_cap(struct link_encoder *enc, struct dc_lin
                if (!query_dp_alt_from_dmub(enc, &cmd))
                        return;
 
-               if (cmd.query_dp_alt.data.is_usb &&
-                   cmd.query_dp_alt.data.is_dp4 == 0)
+               if (cmd.query_dp_alt.data.is_dp_alt_disable == 0 &&
+                               cmd.query_dp_alt.data.is_usb &&
+                               cmd.query_dp_alt.data.is_dp4 == 0)
                        link_settings->lane_count = MIN(LANE_COUNT_TWO, link_settings->lane_count);
 
                return;

diff --git a/drivers/gpu/drm/amd/display/dc/link/link_dpms.c b/drivers/gpu/drm/amd/display/dc/link/link_dpms.c
index b8cfeb98e22997a242a4f29143ff5d6be8c494c3..ec7de9c01fab0196928cbdc48521beb3b18fae4b 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/link/link_dpms.c
+++ b/drivers/gpu/drm/amd/display/dc/link/link_dpms.c
@@ -2548,6 +2548,15 @@ void link_set_dpms_on(
        if (pipe_ctx->stream->dpms_off)
                return;
 
+       /* For Dp tunneling link, a pending HPD means that we have a race condition between processing
+        * current link and processing the pending HPD. If we enable the link now, we may end up with a
+        * link that is not actually connected to a sink. So we skip enabling the link in this case.
+        */
+       if (link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA && link->is_hpd_pending) {
+               DC_LOG_DEBUG("%s, Link%d HPD is pending, not enable it.\n", __func__, link->link_index);
+               return;
+       }
+
        /* Have to setup DSC before DIG FE and BE are connected (which happens before the
         * link training). This is to make sure the bandwidth sent to DIG BE won't be
         * bigger than what the link and/or DIG BE can handle. VBID[6]/CompressedStream_flag

diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c
index d0fbf9c44a29874fa3a4e7149c703c9bbc462711..44c3023a77318d6fefaa9630e3329bc06f45fb2e 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c
+++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c
@@ -2312,6 +2312,14 @@ bool dp_verify_link_cap_with_retries(
                } else {
                        link->verified_link_cap = last_verified_link_cap;
                }
+
+               /* For Dp tunneling link, a pending HPD means that we have a race condition between processing
+                * current link and processing the pending HPD. Since the training is failed, we should just brak
+                * the loop so that we have chance to process the pending HPD.
+                */
+               if (link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA && link->is_hpd_pending)
+                       break;
+
                fsleep(10 * 1000);
        }