[PATCH] Revert "drm/amd/display: Adjust the MST resume flow"

[Mario Limonciello]

This reverts commit ec5fa9fcdeca69edf7dab5ca3b2e0ceb1c08fe9a.

Reports are that this causes problems with external monitors after wake up
from suspend, which is something it was directly supposed to help.

Cc: Linux Regressions <regressions at lists.linux.dev>
Cc: stable at vger.kernel.org
Cc: Daniel Wheeler <daniel.wheeler at amd.com>
Cc: Wayne Lin <wayne.lin at amd.com>
Reported-by: Oliver Schmidt <oliver at luced.de>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218211
Link: https://forum.manjaro.org/t/problems-with-external-monitor-wake-up-after-suspend/151840
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/3023
Signed-off-by: Mario Limonciello <mario.limonciello <mario.limonciello at amd.com>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 93 +++----------------
 1 file changed, 13 insertions(+), 80 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index c146dc9cba92..1ba58e4ecab3 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -2363,62 +2363,14 @@ static int dm_late_init(void *handle)
 	return detect_mst_link_for_all_connectors(adev_to_drm(adev));
 }
 
-static void resume_mst_branch_status(struct drm_dp_mst_topology_mgr *mgr)
-{
-	int ret;
-	u8 guid[16];
-	u64 tmp64;
-
-	mutex_lock(&mgr->lock);
-	if (!mgr->mst_primary)
-		goto out_fail;
-
-	if (drm_dp_read_dpcd_caps(mgr->aux, mgr->dpcd) < 0) {
-		drm_dbg_kms(mgr->dev, "dpcd read failed - undocked during suspend?\n");
-		goto out_fail;
-	}
-
-	ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
-				 DP_MST_EN |
-				 DP_UP_REQ_EN |
-				 DP_UPSTREAM_IS_SRC);
-	if (ret < 0) {
-		drm_dbg_kms(mgr->dev, "mst write failed - undocked during suspend?\n");
-		goto out_fail;
-	}
-
-	/* Some hubs forget their guids after they resume */
-	ret = drm_dp_dpcd_read(mgr->aux, DP_GUID, guid, 16);
-	if (ret != 16) {
-		drm_dbg_kms(mgr->dev, "dpcd read failed - undocked during suspend?\n");
-		goto out_fail;
-	}
-
-	if (memchr_inv(guid, 0, 16) == NULL) {
-		tmp64 = get_jiffies_64();
-		memcpy(&guid[0], &tmp64, sizeof(u64));
-		memcpy(&guid[8], &tmp64, sizeof(u64));
-
-		ret = drm_dp_dpcd_write(mgr->aux, DP_GUID, guid, 16);
-
-		if (ret != 16) {
-			drm_dbg_kms(mgr->dev, "check mstb guid failed - undocked during suspend?\n");
-			goto out_fail;
-		}
-	}
-
-	memcpy(mgr->mst_primary->guid, guid, 16);
-
-out_fail:
-	mutex_unlock(&mgr->lock);
-}
-
 static void s3_handle_mst(struct drm_device *dev, bool suspend)
 {
 	struct amdgpu_dm_connector *aconnector;
 	struct drm_connector *connector;
 	struct drm_connector_list_iter iter;
 	struct drm_dp_mst_topology_mgr *mgr;
+	int ret;
+	bool need_hotplug = false;
 
 	drm_connector_list_iter_begin(dev, &iter);
 	drm_for_each_connector_iter(connector, &iter) {
@@ -2444,15 +2396,18 @@ static void s3_handle_mst(struct drm_device *dev, bool suspend)
 			if (!dp_is_lttpr_present(aconnector->dc_link))
 				try_to_configure_aux_timeout(aconnector->dc_link->ddc, LINK_AUX_DEFAULT_TIMEOUT_PERIOD);
 
-			/* TODO: move resume_mst_branch_status() into drm mst resume again
-			 * once topology probing work is pulled out from mst resume into mst
-			 * resume 2nd step. mst resume 2nd step should be called after old
-			 * state getting restored (i.e. drm_atomic_helper_resume()).
-			 */
-			resume_mst_branch_status(mgr);
+			ret = drm_dp_mst_topology_mgr_resume(mgr, true);
+			if (ret < 0) {
+				dm_helpers_dp_mst_stop_top_mgr(aconnector->dc_link->ctx,
+					aconnector->dc_link);
+				need_hotplug = true;
+			}
 		}
 	}
 	drm_connector_list_iter_end(&iter);
+
+	if (need_hotplug)
+		drm_kms_helper_hotplug_event(dev);
 }
 
 static int amdgpu_dm_smu_write_watermarks_table(struct amdgpu_device *adev)
@@ -2849,8 +2804,7 @@ static int dm_resume(void *handle)
 	struct dm_atomic_state *dm_state = to_dm_atomic_state(dm->atomic_obj.state);
 	enum dc_connection_type new_connection_type = dc_connection_none;
 	struct dc_state *dc_state;
-	int i, r, j, ret;
-	bool need_hotplug = false;
+	int i, r, j;
 
 	if (dm->dc->caps.ips_support) {
 		dc_dmub_srv_exit_low_power_state(dm->dc);
@@ -2957,7 +2911,7 @@ static int dm_resume(void *handle)
 			continue;
 
 		/*
-		 * this is the case when traversing through already created end sink
+		 * this is the case when traversing through already created
 		 * MST connectors, should be skipped
 		 */
 		if (aconnector && aconnector->mst_root)
@@ -3017,27 +2971,6 @@ static int dm_resume(void *handle)
 
 	dm->cached_state = NULL;
 
-	/* Do mst topology probing after resuming cached state*/
-	drm_connector_list_iter_begin(ddev, &iter);
-	drm_for_each_connector_iter(connector, &iter) {
-		aconnector = to_amdgpu_dm_connector(connector);
-		if (aconnector->dc_link->type != dc_connection_mst_branch ||
-		    aconnector->mst_root)
-			continue;
-
-		ret = drm_dp_mst_topology_mgr_resume(&aconnector->mst_mgr, true);
-
-		if (ret < 0) {
-			dm_helpers_dp_mst_stop_top_mgr(aconnector->dc_link->ctx,
-					aconnector->dc_link);
-			need_hotplug = true;
-		}
-	}
-	drm_connector_list_iter_end(&iter);
-
-	if (need_hotplug)
-		drm_kms_helper_hotplug_event(ddev);
-
 	amdgpu_dm_irq_resume_late(adev);
 
 	amdgpu_dm_smu_write_watermarks_table(adev);
-- 
2.34.1