From 65680c3ef346b078af98a8ce7b2f9a06d00628d6 Mon Sep 17 00:00:00 2001
From: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Date: Thu, 25 Nov 2021 10:38:28 -0500
Subject: Documentation/gpu: How to collect DTN log
Git-commit: 76659755b4bf3e73a91c08248dff5a1e6e01db46
Patch-mainline: v5.17-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

Introduce how to collect DTN log from debugfs.

Reviewed-by: Yann Dirson <ydirson@free.fr>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 Documentation/gpu/amdgpu/display/dc-debug.rst | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/Documentation/gpu/amdgpu/display/dc-debug.rst b/Documentation/gpu/amdgpu/display/dc-debug.rst
index 6dbd21f7f59e..40c55a618918 100644
--- a/Documentation/gpu/amdgpu/display/dc-debug.rst
+++ b/Documentation/gpu/amdgpu/display/dc-debug.rst
@@ -58,3 +58,20 @@ In this case, if you have a pipe split, you will see one small red bar at the
 bottom of the display covering the entire display width and another bar
 covering the second pipe. In other words, you will see a bit high bar in the
 second pipe.
+
+DTN Debug
+=========
+
+DC (DCN) provides an extensive log that dumps multiple details from our
+hardware configuration. Via debugfs, you can capture those status values by
+using Display Test Next (DTN) log, which can be captured via debugfs by using::
+
+  cat /sys/kernel/debug/dri/0/amdgpu_dm_dtn_log
+
+Since this log is updated accordingly with DCN status, you can also follow the
+change in real-time by using something like::
+
+  sudo watch -d cat /sys/kernel/debug/dri/0/amdgpu_dm_dtn_log
+
+When reporting a bug related to DC, consider attaching this log before and
+after you reproduce the bug.
-- 
2.38.1