[PATCH 1/9] drm/amd/display: Add debugfs to disallow eDP Replay entry

[ChuanYu Tseng <ChuanYu.Tseng@amd.com>]

From: Ray Wu <ray.wu@amd.com>

[Why & How]
Test applications need to read CRC from eDP sink side, but sink
replay feature prevents proper CRC reading and causing timeout.

Add disallow_edp_enter_replay debugfs interface to allow test apps
to temporarily disable Replay for CRC operations.

Reviewed-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Signed-off-by: Chuanyu Tseng <chuanyu.tseng@amd.com>
---
 .../amd/display/amdgpu_dm/amdgpu_dm_debugfs.c | 52 +++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
index d6d43f1bf6d2..7c6deb2764aa 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
@@ -3305,6 +3305,52 @@ static int disallow_edp_enter_psr_set(void *data, u64 val)
 	return 0;
 }
 
+/* check if kernel disallow eDP enter replay state
+ * cat /sys/kernel/debug/dri/0/eDP-X/disallow_edp_enter_replay
+ * 0: allow edp enter replay; 1: disallow
+ */
+static int disallow_edp_enter_replay_get(void *data, u64 *val)
+{
+	struct amdgpu_dm_connector *aconnector = data;
+
+	*val = (u64) aconnector->disallow_edp_enter_replay;
+	return 0;
+}
+
+/* set kernel disallow eDP enter replay state
+ * echo 0x0 /sys/kernel/debug/dri/0/eDP-X/disallow_edp_enter_replay
+ * 0: allow edp enter replay; 1: disallow
+ *
+ * usage: test app read crc from PSR eDP rx.
+ *
+ * during kernel boot up, kernel write dpcd 0x37b to
+ * notify eDP rx replay enable.
+ * rx fw will start checking crc for rx internal logic.
+ * crc read count within dpcd 0x246 is not updated and
+ * value is 0. when eDP tx driver wants to read rx crc
+ * from dpcd 0x246, 0x270, read count 0 lead tx driver
+ * timeout.
+ *
+ * to avoid this, we add this debugfs to let test app to disbable
+ * rx replay. then test app can read non-zero crc read count.
+ *
+ * expected app sequence is as below:
+ * 1. disable eDP PHY and notify eDP rx with dpcd 0x600 = 2.
+ * 2. echo 0x1 /sys/kernel/debug/dri/0/eDP-X/disallow_edp_enter_replay
+ * 3. enable eDP PHY and notify eDP rx with dpcd 0x600 = 1 but
+ *    without programming dpcd 0x37b.
+ * 4. read crc from rx dpcd 0x270, 0x246, etc.
+ * 5. echo 0x0 /sys/kernel/debug/dri/0/eDP-X/disallow_edp_enter_replay.
+ *    this will let eDP back to normal with replay setup dpcd 0x37b.
+ */
+static int disallow_edp_enter_replay_set(void *data, u64 val)
+{
+	struct amdgpu_dm_connector *aconnector = data;
+
+	aconnector->disallow_edp_enter_replay = val ? true : false;
+	return 0;
+}
+
 static int dmub_trace_mask_set(void *data, u64 val)
 {
 	struct amdgpu_device *adev = data;
@@ -3433,6 +3479,10 @@ DEFINE_DEBUGFS_ATTRIBUTE(disallow_edp_enter_psr_fops,
 			disallow_edp_enter_psr_get,
 			disallow_edp_enter_psr_set, "%llu\n");
 
+DEFINE_DEBUGFS_ATTRIBUTE(disallow_edp_enter_replay_fops,
+			disallow_edp_enter_replay_get,
+			disallow_edp_enter_replay_set, "%llu\n");
+
 DEFINE_DEBUGFS_ATTRIBUTE(ips_residency_cntl_fops, ips_residency_cntl_get,
 			   ips_residency_cntl_set, "%llu\n");
 DEFINE_SHOW_ATTRIBUTE(current_backlight);
@@ -3635,6 +3685,8 @@ void connector_debugfs_init(struct amdgpu_dm_connector *connector)
 					&allow_edp_hotplug_detection_fops);
 		debugfs_create_file("disallow_edp_enter_psr", 0644, dir, connector,
 					&disallow_edp_enter_psr_fops);
+		debugfs_create_file("disallow_edp_enter_replay", 0644, dir, connector,
+					&disallow_edp_enter_replay_fops);
 	}
 
 	for (i = 0; i < ARRAY_SIZE(connector_debugfs_entries); i++) {
-- 
2.43.0