From 2df70772711d01e67a32db1398200c49aa3c085c Mon Sep 17 00:00:00 2001
From: Wang Fudong <Fudong.Wang@amd.com>
Date: Wed, 17 Aug 2022 17:47:50 +0800
Subject: drm/amd/display: set dig fifo read start level to 7 before dig fifo
reset
Git-commit: 3e834a17a22cb8e9169c0b018d1a2df126977db3
Patch-mainline: v6.0-rc4
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 jsc#PED-2849
[Why]
DIG_FIFO_ERROR = 1 caused mst daisy chain 2nd monitor black.
[How]
We need to set dig fifo read start level = 7 before dig fifo reset during dig
fifo enable according to hardware designer's suggestion. If it is zero, it will
cause underflow or overflow and DIG_FIFO_ERROR = 1.
Reviewed-by: Alvin Lee <Alvin.Lee2@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Brian Chang <Brian.Chang@amd.com>
Signed-off-by: Wang Fudong <Fudong.Wang@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
.../gpu/drm/amd/display/dc/dcn32/dcn32_dio_stream_encoder.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dio_stream_encoder.c b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dio_stream_encoder.c
index 26648ce772da..38a48983f663 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dio_stream_encoder.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dio_stream_encoder.c
@@ -310,6 +310,11 @@ static void enc32_stream_encoder_dp_unblank(
// TODO: Confirm if we need to wait for DIG_SYMCLK_FE_ON
REG_WAIT(DIG_FE_CNTL, DIG_SYMCLK_FE_ON, 1, 10, 5000);
+ /* read start level = 0 will bring underflow / overflow and DIG_FIFO_ERROR = 1
+ * so set it to 1/2 full = 7 before reset as suggested by hardware team.
+ */
+ REG_UPDATE(DIG_FIFO_CTRL0, DIG_FIFO_READ_START_LEVEL, 0x7);
+
REG_UPDATE(DIG_FIFO_CTRL0, DIG_FIFO_RESET, 1);
REG_WAIT(DIG_FIFO_CTRL0, DIG_FIFO_RESET_DONE, 1, 10, 5000);
--
2.38.1